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Page 1 Exercise 2.1 1. Find the zeroes of each of the following quadratic polynomials and verify the relationship between the zeroes and their co efficient: (i) f(x) = ?? 2 - 2?? - 8 (ii) g(s) = 4?? 2 - 4?? + 1 (iii) h(t) = ?? 2 - 15 (iv) p(x) = ?? 2 + 2v2?? + 6 (v) q(x) = v3?? 2 + 10?? + 7v3 (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 (vii) g(x) = ?? ( ?? 2 + 1)- ?? ( ?? 2 + 1) (viii) 6?? 2 - 3 - 7?? Sol: (i) f(x) = ?? 2 - 2?? - 8 ?? ( ?? ) = ?? 2 - 2?? - 8 = ?? 2 - 4?? + 2?? - 8 = ?? ( ?? - 4)+ 2( ?? - 4) = ( ?? + 2) ( ?? - 4) Zeroes of the polynomials are -2 and 4 Sum of the zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? -2 + 4 = -( -2) 1 2 = 2 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = 24 = -8 1 - 8 = -8 ? Hence the relationship verified (ii) 9( 5) = 45 - 45 + 1 = 45 2 - 25 - 25 + 1 = 25( 25 - 1)- 1( 25 - 1) = ( 25 - 1) ( 25 - 1) Zeroes of the polynomials are 1 2 ?????? 1 2 Sum of zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? 2 1 2 + 1 2 = -( -4) 4 1 = 1 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 1 2 × 1 2 = 1 4 ? 1 4 = 1 4 ? Hence the relationship verified. (iii) h(t) = ?? 2 - 15 = ( ?? 2 )- ( v15) 2 = ( ?? + v15) ( ?? - v15) zeroes of the polynomials are -v15 ?????? v15 sum of zeroes = 0 -v15 + v15 = 0 0 = 0 Page 2 Exercise 2.1 1. Find the zeroes of each of the following quadratic polynomials and verify the relationship between the zeroes and their co efficient: (i) f(x) = ?? 2 - 2?? - 8 (ii) g(s) = 4?? 2 - 4?? + 1 (iii) h(t) = ?? 2 - 15 (iv) p(x) = ?? 2 + 2v2?? + 6 (v) q(x) = v3?? 2 + 10?? + 7v3 (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 (vii) g(x) = ?? ( ?? 2 + 1)- ?? ( ?? 2 + 1) (viii) 6?? 2 - 3 - 7?? Sol: (i) f(x) = ?? 2 - 2?? - 8 ?? ( ?? ) = ?? 2 - 2?? - 8 = ?? 2 - 4?? + 2?? - 8 = ?? ( ?? - 4)+ 2( ?? - 4) = ( ?? + 2) ( ?? - 4) Zeroes of the polynomials are -2 and 4 Sum of the zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? -2 + 4 = -( -2) 1 2 = 2 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = 24 = -8 1 - 8 = -8 ? Hence the relationship verified (ii) 9( 5) = 45 - 45 + 1 = 45 2 - 25 - 25 + 1 = 25( 25 - 1)- 1( 25 - 1) = ( 25 - 1) ( 25 - 1) Zeroes of the polynomials are 1 2 ?????? 1 2 Sum of zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? 2 1 2 + 1 2 = -( -4) 4 1 = 1 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 1 2 × 1 2 = 1 4 ? 1 4 = 1 4 ? Hence the relationship verified. (iii) h(t) = ?? 2 - 15 = ( ?? 2 )- ( v15) 2 = ( ?? + v15) ( ?? - v15) zeroes of the polynomials are -v15 ?????? v15 sum of zeroes = 0 -v15 + v15 = 0 0 = 0 Product of zeroes = -15 1 -v15 × v15 = -15 -15 = -15 ? Hence the relationship verified. (iv) p(x) = ?? 2 + 2v2?? - 6 = ?? 2 + 3v2?? + v2 × 3v2 = ?? ( ?? + 3v2)- v2( 2 + 3v2) = ( ?? - v2) ( ?? + 3v2) Zeroes of the polynomial are 3v2 and -3v2 Sum of the zeroes = -3v2 1 v2 - 3v2 = -2v2 -2v2 = -2v2 ?????????????? ???? ???????????? ? v2 × -3v2 = - 6 1 -6 = -6 ?????????? ?? h?? ???????????????? h???? ???????????????? (v) 2(x) = v3?? 2 + 10?? + 7v3 = v3?? 2 + 7?? + 3?? + 7v3 = v3?? ( ?? + v3)+ 7( ?? + v3) = ( v3?? + 7) ( ?? + v3) Zeroes of the polynomials are -v3, -7 v3 Sum of zeroes = -10 v3 ? -v3 - 7 v3 = -10 v3 ? -10 v3 = -10 v3 Product of zeroes = 7v3 3 ? v3?? -7 v30 = 7 ? 7 = 7 Hence, relationship verified. (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 = ?? 2 - v3?? - ?? + v3 = x (x - v3) – 1 (x - v3) = (x – 1) (x - v3) Zeroes of the polynomials are 1 and v3 Sum of zeroes = -{?????????????????????? ???? ?? } ???? ?????????????????? ???? ?? 2 = -[-v3-1] 1 1 + v3 = v3 + 1 Product of zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = v3 1 1 × v3 = v3 = v3 = v3 ? Hence, relationship verified (vii) g(x) = ?? [( ?? 2 + 1)- ?? ( ?? 2 + 1) ] 2 = ?? ?? 2 + ?? - ?? 2 ?? - ?? = ?? ?? 2 - [( ?? 2 + 1)- ?? ] + 0 = ?? ?? 2 - ?? 2 ?? - ?? + ?? Page 3 Exercise 2.1 1. Find the zeroes of each of the following quadratic polynomials and verify the relationship between the zeroes and their co efficient: (i) f(x) = ?? 2 - 2?? - 8 (ii) g(s) = 4?? 2 - 4?? + 1 (iii) h(t) = ?? 2 - 15 (iv) p(x) = ?? 2 + 2v2?? + 6 (v) q(x) = v3?? 2 + 10?? + 7v3 (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 (vii) g(x) = ?? ( ?? 2 + 1)- ?? ( ?? 2 + 1) (viii) 6?? 2 - 3 - 7?? Sol: (i) f(x) = ?? 2 - 2?? - 8 ?? ( ?? ) = ?? 2 - 2?? - 8 = ?? 2 - 4?? + 2?? - 8 = ?? ( ?? - 4)+ 2( ?? - 4) = ( ?? + 2) ( ?? - 4) Zeroes of the polynomials are -2 and 4 Sum of the zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? -2 + 4 = -( -2) 1 2 = 2 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = 24 = -8 1 - 8 = -8 ? Hence the relationship verified (ii) 9( 5) = 45 - 45 + 1 = 45 2 - 25 - 25 + 1 = 25( 25 - 1)- 1( 25 - 1) = ( 25 - 1) ( 25 - 1) Zeroes of the polynomials are 1 2 ?????? 1 2 Sum of zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? 2 1 2 + 1 2 = -( -4) 4 1 = 1 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 1 2 × 1 2 = 1 4 ? 1 4 = 1 4 ? Hence the relationship verified. (iii) h(t) = ?? 2 - 15 = ( ?? 2 )- ( v15) 2 = ( ?? + v15) ( ?? - v15) zeroes of the polynomials are -v15 ?????? v15 sum of zeroes = 0 -v15 + v15 = 0 0 = 0 Product of zeroes = -15 1 -v15 × v15 = -15 -15 = -15 ? Hence the relationship verified. (iv) p(x) = ?? 2 + 2v2?? - 6 = ?? 2 + 3v2?? + v2 × 3v2 = ?? ( ?? + 3v2)- v2( 2 + 3v2) = ( ?? - v2) ( ?? + 3v2) Zeroes of the polynomial are 3v2 and -3v2 Sum of the zeroes = -3v2 1 v2 - 3v2 = -2v2 -2v2 = -2v2 ?????????????? ???? ???????????? ? v2 × -3v2 = - 6 1 -6 = -6 ?????????? ?? h?? ???????????????? h???? ???????????????? (v) 2(x) = v3?? 2 + 10?? + 7v3 = v3?? 2 + 7?? + 3?? + 7v3 = v3?? ( ?? + v3)+ 7( ?? + v3) = ( v3?? + 7) ( ?? + v3) Zeroes of the polynomials are -v3, -7 v3 Sum of zeroes = -10 v3 ? -v3 - 7 v3 = -10 v3 ? -10 v3 = -10 v3 Product of zeroes = 7v3 3 ? v3?? -7 v30 = 7 ? 7 = 7 Hence, relationship verified. (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 = ?? 2 - v3?? - ?? + v3 = x (x - v3) – 1 (x - v3) = (x – 1) (x - v3) Zeroes of the polynomials are 1 and v3 Sum of zeroes = -{?????????????????????? ???? ?? } ???? ?????????????????? ???? ?? 2 = -[-v3-1] 1 1 + v3 = v3 + 1 Product of zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = v3 1 1 × v3 = v3 = v3 = v3 ? Hence, relationship verified (vii) g(x) = ?? [( ?? 2 + 1)- ?? ( ?? 2 + 1) ] 2 = ?? ?? 2 + ?? - ?? 2 ?? - ?? = ?? ?? 2 - [( ?? 2 + 1)- ?? ] + 0 = ?? ?? 2 - ?? 2 ?? - ?? + ?? = ???? ( ?? - ?? )- 1( ?? - ?? ) = ( ?? - ?? ) ( ???? - 1) Zeroes of the polynomials = 1 ?? ?????? ?? Sum of the zeroes = -[-?? 2 -1] ?? ? 1 ?? + ?? = ?? 2 +1 ?? ? ?? 2 +1 ?? = ?? 2 +1 ?? Product of zeroes = ?? ?? ? 1 ?? × ?? = ?? ?? ? ?? 2 +1 ?? = ?? 2 +1 ?? Product of zeroes = ?? ?? ? 1 = 1 Hence relationship verified (viii) 6?? 2 - 3 - 7?? = 6?? 2 - 7?? - 3 = ( 3?? + 11) ( 2?? - 3) Zeroes of polynomials are + 3 2 ?????? -1 3 Sum of zeroes = -1 3 + 3 2 = 7 6 = -( -7) 6 = -( ???? ?????????????????? ???? ?? ) ???? ?????????????????? ???? ?? 2 Product of zeroes = -1 3 × 3 2 = -1 2 = -3 6 = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 ? Hence, relationship verified. 2. If ?? and ?? are the zeros of the quadratic polynomial f(x) = ax 2 + bx + c, then evaluate: (i) ?? - ?? (ii) 1 ?? - 1 ?? (iii) 1 ?? + 1 ?? - 2?? ?? (iv) ?? 2 ?? + ?? ?? 2 (v) ?? 4 + ?? 4 (vi) 1 ???? +?? + 1 ???? +?? (vii) ?? ???? +?? + ?? ???? +?? (viii) ?? [ ?? 2 ?? + ?? 2 ?? ] + ?? [ ?? ?? + ?? ?? ] Sol: f(x) = ?? ?? 2 + ???? + ?? ?? + ?? = -?? ?? ???? = ?? ?? ?????????? ?? + ?? ?????? ?? h?? ?????????? ( ???? ) ???????????? ???? ?? h?? ?????????? ?????????????????????? (i) ?? - ?? The two zeroes of the polynomials are -?? +v?? 2 -4???? 2?? - (?? -v?? 2 -4???? 2?? ) = -?? + v?? 2 -4???? +?? +v?? 2 -4???? 2?? = 2v?? 2 -4???? 2?? = v?? 2 -4???? 2?? (ii) 1 ?? - 1 ?? = ?? -?? ???? = -( ?? - ?? ) ???? … ( ?? ) From (i) we know that ?? - ?? = v?? 2 -4???? 2?? [???????? ( ?? ) ]???? = ?? ?? Putting the values in the (a) = - ( v?? 2 -4???? ×?? ?? ×?? ) = -v?? 2 -4???? ?? (iii) 1 ?? + 1 ?? - 2?? ?? Page 4 Exercise 2.1 1. Find the zeroes of each of the following quadratic polynomials and verify the relationship between the zeroes and their co efficient: (i) f(x) = ?? 2 - 2?? - 8 (ii) g(s) = 4?? 2 - 4?? + 1 (iii) h(t) = ?? 2 - 15 (iv) p(x) = ?? 2 + 2v2?? + 6 (v) q(x) = v3?? 2 + 10?? + 7v3 (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 (vii) g(x) = ?? ( ?? 2 + 1)- ?? ( ?? 2 + 1) (viii) 6?? 2 - 3 - 7?? Sol: (i) f(x) = ?? 2 - 2?? - 8 ?? ( ?? ) = ?? 2 - 2?? - 8 = ?? 2 - 4?? + 2?? - 8 = ?? ( ?? - 4)+ 2( ?? - 4) = ( ?? + 2) ( ?? - 4) Zeroes of the polynomials are -2 and 4 Sum of the zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? -2 + 4 = -( -2) 1 2 = 2 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = 24 = -8 1 - 8 = -8 ? Hence the relationship verified (ii) 9( 5) = 45 - 45 + 1 = 45 2 - 25 - 25 + 1 = 25( 25 - 1)- 1( 25 - 1) = ( 25 - 1) ( 25 - 1) Zeroes of the polynomials are 1 2 ?????? 1 2 Sum of zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? 2 1 2 + 1 2 = -( -4) 4 1 = 1 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 1 2 × 1 2 = 1 4 ? 1 4 = 1 4 ? Hence the relationship verified. (iii) h(t) = ?? 2 - 15 = ( ?? 2 )- ( v15) 2 = ( ?? + v15) ( ?? - v15) zeroes of the polynomials are -v15 ?????? v15 sum of zeroes = 0 -v15 + v15 = 0 0 = 0 Product of zeroes = -15 1 -v15 × v15 = -15 -15 = -15 ? Hence the relationship verified. (iv) p(x) = ?? 2 + 2v2?? - 6 = ?? 2 + 3v2?? + v2 × 3v2 = ?? ( ?? + 3v2)- v2( 2 + 3v2) = ( ?? - v2) ( ?? + 3v2) Zeroes of the polynomial are 3v2 and -3v2 Sum of the zeroes = -3v2 1 v2 - 3v2 = -2v2 -2v2 = -2v2 ?????????????? ???? ???????????? ? v2 × -3v2 = - 6 1 -6 = -6 ?????????? ?? h?? ???????????????? h???? ???????????????? (v) 2(x) = v3?? 2 + 10?? + 7v3 = v3?? 2 + 7?? + 3?? + 7v3 = v3?? ( ?? + v3)+ 7( ?? + v3) = ( v3?? + 7) ( ?? + v3) Zeroes of the polynomials are -v3, -7 v3 Sum of zeroes = -10 v3 ? -v3 - 7 v3 = -10 v3 ? -10 v3 = -10 v3 Product of zeroes = 7v3 3 ? v3?? -7 v30 = 7 ? 7 = 7 Hence, relationship verified. (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 = ?? 2 - v3?? - ?? + v3 = x (x - v3) – 1 (x - v3) = (x – 1) (x - v3) Zeroes of the polynomials are 1 and v3 Sum of zeroes = -{?????????????????????? ???? ?? } ???? ?????????????????? ???? ?? 2 = -[-v3-1] 1 1 + v3 = v3 + 1 Product of zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = v3 1 1 × v3 = v3 = v3 = v3 ? Hence, relationship verified (vii) g(x) = ?? [( ?? 2 + 1)- ?? ( ?? 2 + 1) ] 2 = ?? ?? 2 + ?? - ?? 2 ?? - ?? = ?? ?? 2 - [( ?? 2 + 1)- ?? ] + 0 = ?? ?? 2 - ?? 2 ?? - ?? + ?? = ???? ( ?? - ?? )- 1( ?? - ?? ) = ( ?? - ?? ) ( ???? - 1) Zeroes of the polynomials = 1 ?? ?????? ?? Sum of the zeroes = -[-?? 2 -1] ?? ? 1 ?? + ?? = ?? 2 +1 ?? ? ?? 2 +1 ?? = ?? 2 +1 ?? Product of zeroes = ?? ?? ? 1 ?? × ?? = ?? ?? ? ?? 2 +1 ?? = ?? 2 +1 ?? Product of zeroes = ?? ?? ? 1 = 1 Hence relationship verified (viii) 6?? 2 - 3 - 7?? = 6?? 2 - 7?? - 3 = ( 3?? + 11) ( 2?? - 3) Zeroes of polynomials are + 3 2 ?????? -1 3 Sum of zeroes = -1 3 + 3 2 = 7 6 = -( -7) 6 = -( ???? ?????????????????? ???? ?? ) ???? ?????????????????? ???? ?? 2 Product of zeroes = -1 3 × 3 2 = -1 2 = -3 6 = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 ? Hence, relationship verified. 2. If ?? and ?? are the zeros of the quadratic polynomial f(x) = ax 2 + bx + c, then evaluate: (i) ?? - ?? (ii) 1 ?? - 1 ?? (iii) 1 ?? + 1 ?? - 2?? ?? (iv) ?? 2 ?? + ?? ?? 2 (v) ?? 4 + ?? 4 (vi) 1 ???? +?? + 1 ???? +?? (vii) ?? ???? +?? + ?? ???? +?? (viii) ?? [ ?? 2 ?? + ?? 2 ?? ] + ?? [ ?? ?? + ?? ?? ] Sol: f(x) = ?? ?? 2 + ???? + ?? ?? + ?? = -?? ?? ???? = ?? ?? ?????????? ?? + ?? ?????? ?? h?? ?????????? ( ???? ) ???????????? ???? ?? h?? ?????????? ?????????????????????? (i) ?? - ?? The two zeroes of the polynomials are -?? +v?? 2 -4???? 2?? - (?? -v?? 2 -4???? 2?? ) = -?? + v?? 2 -4???? +?? +v?? 2 -4???? 2?? = 2v?? 2 -4???? 2?? = v?? 2 -4???? 2?? (ii) 1 ?? - 1 ?? = ?? -?? ???? = -( ?? - ?? ) ???? … ( ?? ) From (i) we know that ?? - ?? = v?? 2 -4???? 2?? [???????? ( ?? ) ]???? = ?? ?? Putting the values in the (a) = - ( v?? 2 -4???? ×?? ?? ×?? ) = -v?? 2 -4???? ?? (iii) 1 ?? + 1 ?? - 2?? ?? ? [ ?? + ?? ???? ] - 2???? ? -?? ?? × ?? ?? - 2 ?? ?? = -2 ?? ?? - ?? ?? = -???? -2?? 2 ???? - [ ?? ?? + 2?? ?? ] (iv) ?? 2 ?? + ?? ?? 2 ?? ?? ( ?? + ?? ) = ?? ?? ( -?? ?? ) = -???? ?? 2 (v) ?? 4 + ?? 4 = ( ?? 2 + ?? 2 ) 2 - 2?? 2 + ?? 2 = ( ( ?? + ?? ) 2 - 2???? ) 2 - 2( ???? ) 2 = [(- ?? ?? ) 2 - 2 ?? ?? ] 2 - [2 ( ?? ?? ) 2 ] = [ ?? 2 -2???? ?? 2 ] 2 - 2?? 2 ?? 2 = ( ?? 2 2???? ) 2 -2?? 2 ?? 2 ?? 4 (vi) 1 ???? +?? + 1 ???? +?? ? ???? +?? +???? +?? ( 3?? +?? ) ( ???? +?? ) = ?? ( ?? + ?? ) +2?? ?? 2 ???? +???? ?? +?????? +?? 2 = ?? ( ?? +?? ) +?? ?? 2 ???? +???? ( ?? 2 ?? ) +?? 2 = ?? × ?? +2?? ?? ?? × ?? ?? + ?????? ( -?? ) +?? 2 ?? = ?? ???? -?? 2 +?? 2 = ?? ???? (vii) ?? ???? +?? + ?? ???? +?? = ?? ( ???? +?? ) +?? ( ???? +?? ) ( ???? +?? ) ( ???? +?? ) = ?? ?? 2 +???? +?? ?? 2 +???? ?? 2 ???? +?????? +?????? +?? 2 = ?? ?? 2 +?? ?? 2 +?? ?? 2 +???? ?? × ?? ?? +???? ( ?? +?? ) +?? 2 = ?? [( ?? 2 +?? 2 ) +?? ( ?? +?? ) ] ???? +???? +?? ( -?? ?? )+?? 2 = ?? [( ?? + ?? ) 2 -2???? ]+???? - ?? ?? ???? = ?? [ ?? 2 ?? - 2?? ?? ]- ?? 2 ?? ???? = ?? ×[ ?? 2 -2?? ?? ]-?? 2 ???? = -2 ?? (viii) ?? [ ?? 2 ?? + ?? 2 ?? ] + ?? [ ?? ?? + ?? ?? ] = ?? [ ?? 3 +?? 3 ???? ] + ?? ( ?? 2 +?? 2 ???? ) Page 5 Exercise 2.1 1. Find the zeroes of each of the following quadratic polynomials and verify the relationship between the zeroes and their co efficient: (i) f(x) = ?? 2 - 2?? - 8 (ii) g(s) = 4?? 2 - 4?? + 1 (iii) h(t) = ?? 2 - 15 (iv) p(x) = ?? 2 + 2v2?? + 6 (v) q(x) = v3?? 2 + 10?? + 7v3 (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 (vii) g(x) = ?? ( ?? 2 + 1)- ?? ( ?? 2 + 1) (viii) 6?? 2 - 3 - 7?? Sol: (i) f(x) = ?? 2 - 2?? - 8 ?? ( ?? ) = ?? 2 - 2?? - 8 = ?? 2 - 4?? + 2?? - 8 = ?? ( ?? - 4)+ 2( ?? - 4) = ( ?? + 2) ( ?? - 4) Zeroes of the polynomials are -2 and 4 Sum of the zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? -2 + 4 = -( -2) 1 2 = 2 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = 24 = -8 1 - 8 = -8 ? Hence the relationship verified (ii) 9( 5) = 45 - 45 + 1 = 45 2 - 25 - 25 + 1 = 25( 25 - 1)- 1( 25 - 1) = ( 25 - 1) ( 25 - 1) Zeroes of the polynomials are 1 2 ?????? 1 2 Sum of zeroes = - ???? ?????????????????? ???? ?? ???? ?????????????????? ???? ?? 2 1 2 + 1 2 = -( -4) 4 1 = 1 Product of the zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 1 2 × 1 2 = 1 4 ? 1 4 = 1 4 ? Hence the relationship verified. (iii) h(t) = ?? 2 - 15 = ( ?? 2 )- ( v15) 2 = ( ?? + v15) ( ?? - v15) zeroes of the polynomials are -v15 ?????? v15 sum of zeroes = 0 -v15 + v15 = 0 0 = 0 Product of zeroes = -15 1 -v15 × v15 = -15 -15 = -15 ? Hence the relationship verified. (iv) p(x) = ?? 2 + 2v2?? - 6 = ?? 2 + 3v2?? + v2 × 3v2 = ?? ( ?? + 3v2)- v2( 2 + 3v2) = ( ?? - v2) ( ?? + 3v2) Zeroes of the polynomial are 3v2 and -3v2 Sum of the zeroes = -3v2 1 v2 - 3v2 = -2v2 -2v2 = -2v2 ?????????????? ???? ???????????? ? v2 × -3v2 = - 6 1 -6 = -6 ?????????? ?? h?? ???????????????? h???? ???????????????? (v) 2(x) = v3?? 2 + 10?? + 7v3 = v3?? 2 + 7?? + 3?? + 7v3 = v3?? ( ?? + v3)+ 7( ?? + v3) = ( v3?? + 7) ( ?? + v3) Zeroes of the polynomials are -v3, -7 v3 Sum of zeroes = -10 v3 ? -v3 - 7 v3 = -10 v3 ? -10 v3 = -10 v3 Product of zeroes = 7v3 3 ? v3?? -7 v30 = 7 ? 7 = 7 Hence, relationship verified. (vi) f(x) = ?? 2 - ( v3 + 1) ?? + v3 = ?? 2 - v3?? - ?? + v3 = x (x - v3) – 1 (x - v3) = (x – 1) (x - v3) Zeroes of the polynomials are 1 and v3 Sum of zeroes = -{?????????????????????? ???? ?? } ???? ?????????????????? ???? ?? 2 = -[-v3-1] 1 1 + v3 = v3 + 1 Product of zeroes = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 = v3 1 1 × v3 = v3 = v3 = v3 ? Hence, relationship verified (vii) g(x) = ?? [( ?? 2 + 1)- ?? ( ?? 2 + 1) ] 2 = ?? ?? 2 + ?? - ?? 2 ?? - ?? = ?? ?? 2 - [( ?? 2 + 1)- ?? ] + 0 = ?? ?? 2 - ?? 2 ?? - ?? + ?? = ???? ( ?? - ?? )- 1( ?? - ?? ) = ( ?? - ?? ) ( ???? - 1) Zeroes of the polynomials = 1 ?? ?????? ?? Sum of the zeroes = -[-?? 2 -1] ?? ? 1 ?? + ?? = ?? 2 +1 ?? ? ?? 2 +1 ?? = ?? 2 +1 ?? Product of zeroes = ?? ?? ? 1 ?? × ?? = ?? ?? ? ?? 2 +1 ?? = ?? 2 +1 ?? Product of zeroes = ?? ?? ? 1 = 1 Hence relationship verified (viii) 6?? 2 - 3 - 7?? = 6?? 2 - 7?? - 3 = ( 3?? + 11) ( 2?? - 3) Zeroes of polynomials are + 3 2 ?????? -1 3 Sum of zeroes = -1 3 + 3 2 = 7 6 = -( -7) 6 = -( ???? ?????????????????? ???? ?? ) ???? ?????????????????? ???? ?? 2 Product of zeroes = -1 3 × 3 2 = -1 2 = -3 6 = ???????????????? ???????? ???? ?????????????????? ???? ?? 2 ? Hence, relationship verified. 2. If ?? and ?? are the zeros of the quadratic polynomial f(x) = ax 2 + bx + c, then evaluate: (i) ?? - ?? (ii) 1 ?? - 1 ?? (iii) 1 ?? + 1 ?? - 2?? ?? (iv) ?? 2 ?? + ?? ?? 2 (v) ?? 4 + ?? 4 (vi) 1 ???? +?? + 1 ???? +?? (vii) ?? ???? +?? + ?? ???? +?? (viii) ?? [ ?? 2 ?? + ?? 2 ?? ] + ?? [ ?? ?? + ?? ?? ] Sol: f(x) = ?? ?? 2 + ???? + ?? ?? + ?? = -?? ?? ???? = ?? ?? ?????????? ?? + ?? ?????? ?? h?? ?????????? ( ???? ) ???????????? ???? ?? h?? ?????????? ?????????????????????? (i) ?? - ?? The two zeroes of the polynomials are -?? +v?? 2 -4???? 2?? - (?? -v?? 2 -4???? 2?? ) = -?? + v?? 2 -4???? +?? +v?? 2 -4???? 2?? = 2v?? 2 -4???? 2?? = v?? 2 -4???? 2?? (ii) 1 ?? - 1 ?? = ?? -?? ???? = -( ?? - ?? ) ???? … ( ?? ) From (i) we know that ?? - ?? = v?? 2 -4???? 2?? [???????? ( ?? ) ]???? = ?? ?? Putting the values in the (a) = - ( v?? 2 -4???? ×?? ?? ×?? ) = -v?? 2 -4???? ?? (iii) 1 ?? + 1 ?? - 2?? ?? ? [ ?? + ?? ???? ] - 2???? ? -?? ?? × ?? ?? - 2 ?? ?? = -2 ?? ?? - ?? ?? = -???? -2?? 2 ???? - [ ?? ?? + 2?? ?? ] (iv) ?? 2 ?? + ?? ?? 2 ?? ?? ( ?? + ?? ) = ?? ?? ( -?? ?? ) = -???? ?? 2 (v) ?? 4 + ?? 4 = ( ?? 2 + ?? 2 ) 2 - 2?? 2 + ?? 2 = ( ( ?? + ?? ) 2 - 2???? ) 2 - 2( ???? ) 2 = [(- ?? ?? ) 2 - 2 ?? ?? ] 2 - [2 ( ?? ?? ) 2 ] = [ ?? 2 -2???? ?? 2 ] 2 - 2?? 2 ?? 2 = ( ?? 2 2???? ) 2 -2?? 2 ?? 2 ?? 4 (vi) 1 ???? +?? + 1 ???? +?? ? ???? +?? +???? +?? ( 3?? +?? ) ( ???? +?? ) = ?? ( ?? + ?? ) +2?? ?? 2 ???? +???? ?? +?????? +?? 2 = ?? ( ?? +?? ) +?? ?? 2 ???? +???? ( ?? 2 ?? ) +?? 2 = ?? × ?? +2?? ?? ?? × ?? ?? + ?????? ( -?? ) +?? 2 ?? = ?? ???? -?? 2 +?? 2 = ?? ???? (vii) ?? ???? +?? + ?? ???? +?? = ?? ( ???? +?? ) +?? ( ???? +?? ) ( ???? +?? ) ( ???? +?? ) = ?? ?? 2 +???? +?? ?? 2 +???? ?? 2 ???? +?????? +?????? +?? 2 = ?? ?? 2 +?? ?? 2 +?? ?? 2 +???? ?? × ?? ?? +???? ( ?? +?? ) +?? 2 = ?? [( ?? 2 +?? 2 ) +?? ( ?? +?? ) ] ???? +???? +?? ( -?? ?? )+?? 2 = ?? [( ?? + ?? ) 2 -2???? ]+???? - ?? ?? ???? = ?? [ ?? 2 ?? - 2?? ?? ]- ?? 2 ?? ???? = ?? ×[ ?? 2 -2?? ?? ]-?? 2 ???? = -2 ?? (viii) ?? [ ?? 2 ?? + ?? 2 ?? ] + ?? [ ?? ?? + ?? ?? ] = ?? [ ?? 3 +?? 3 ???? ] + ?? ( ?? 2 +?? 2 ???? ) = ?? [( ?? +?? ) 3 -3???? ( ?? +?? ) ] ?? ?? + ?? ( ?? + ?? ) 2 - 2?? ?? = ?? [( -?? 3 ?? 3 )+ 3?? ?? . ?? ?? +?? ( ?? 2 ?? 2 - 2?? ?? )] ?? ?? = ?? 2 ?? [ -?? 3 ?? 3 + 3???? ?? 2 + ?? 3 ?? 2 - 2???? ?? ] = -?? 2 ?? 3 ?? ?? 3 + 3?? 2 ???? ?? ?? 2 + ?? 3 ?? 2 ?? 2 ?? - 2???? ?? 2 ???? = -?? 3 ???? + 3?? + ?? 3 ???? - 2?? = b 3. If ?? and ?? are the zeros of the quadratic polynomial f(x) = 6x 2 + x - 2, find the value of ?? ?? + ?? ?? Sol: f(x) = 6?? 2 - ?? - 2 Since ?? and ?? are the zeroes of the given polynomial ? Sum of zeroes [?? + ?? ] = -1 6 Product of zeroes (???? ) = -1 3 = ?? ?? + ?? ?? = ?? 2 +?? 2 ???? = ( ?? + ?? ) 2 -2???? ???? = ( 1 6 ) 2 -2×( -1 3 ) - 1 3 = 1 6 - 2 3 -1 3 = 1+24 36 -1 3 = 2 36 1 3 = -25 12 4. If a and are the zeros of the quadratic polynomial f(x) = ?? 2 - ?? - 4, find the value of 1 ?? + 1 ?? - ???? Sol: Since ?? + ?? are the zeroes of the polynomial: ?? 2 - ?? - 4 Sum of the roots (?? + ?? ) = 1 Product of the roots (???? ) = -4 1 ?? + 1 ?? - ???? = ?? +?? ???? - ???? = 1 -4 + 4 = -1 4 + 4 = -1+16 4 = 15 4 5. If ?? and ?? are the zeros of the quadratic polynomial p(x) = 4x 2 - 5x -1, find the value of ?? 2 ?? + ?? ?? 2 . Sol: Since ?? ?????? ?? are the roots of the polynomial: 4?? 2 - 5?? - 1Read More
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