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Page 1 Exercise 5.1 Page No: 5.4 1. Add the following rational numbers: (i) (-5/7) and (3/7) (ii) (-15/4) and (7/4) (iii) (-8/11) and (-4/11) (iv) (6/13) and (-9/13) Solution: (i) Given (-5/7) and (3/7) = (-5/7) + (3/7) Here denominators are same so add the numerator = ((-5+3)/7) = (-2/7) (ii) Given (-15/4) and (7/4) = (-15/4) + (7/4) Here denominators are same so add the numerator = ((-15 + 7)/4) = (-8/4) On simplifying = -2 (iii) Given (-8/11) and (-4/11) = (-8/11) + (-4/11) Here denominators are same so add the numerator = (-8 + (-4))/11 = (-12/11) (iv) Given (6/13) and (-9/13) = (6/13) + (-9/13) Here denominators are same so add the numerator = (6 + (-9))/13 = (-3/13) 2. Add the following rational numbers: (i) (3/4) and (-3/5) Page 2 Exercise 5.1 Page No: 5.4 1. Add the following rational numbers: (i) (-5/7) and (3/7) (ii) (-15/4) and (7/4) (iii) (-8/11) and (-4/11) (iv) (6/13) and (-9/13) Solution: (i) Given (-5/7) and (3/7) = (-5/7) + (3/7) Here denominators are same so add the numerator = ((-5+3)/7) = (-2/7) (ii) Given (-15/4) and (7/4) = (-15/4) + (7/4) Here denominators are same so add the numerator = ((-15 + 7)/4) = (-8/4) On simplifying = -2 (iii) Given (-8/11) and (-4/11) = (-8/11) + (-4/11) Here denominators are same so add the numerator = (-8 + (-4))/11 = (-12/11) (iv) Given (6/13) and (-9/13) = (6/13) + (-9/13) Here denominators are same so add the numerator = (6 + (-9))/13 = (-3/13) 2. Add the following rational numbers: (i) (3/4) and (-3/5) (ii) -3 and (3/5) (iii) (-7/27) and (11/18) (iv) (31/-4) and (-5/8) Solution: (i) Given (3/4) and (-3/5) If p/q and r/s are two rational numbers such that q and s do not have a common factor other than one, then (p/q) + (r/s) = (p × s + r × q)/ (q × s) (3/4) + (-3/5) = (3 × 5 + (-3) × 4)/ (4 × 5) = (15 – 12)/ 20 = (3/20) (ii) Given -3 and (3/5) If p/q and r/s are two rational numbers such that q and s do not have a common factor other than one, then (p/q) + (r/s) = (p × s + r × q)/ (q × s) (-3/1) + (3/5) = (-3 × 5 + 3 × 1)/ (1 × 5) = (-15 + 3)/ 5 = (-12/5) (iii) Given (-7/27) and (11/18) LCM of 27 and 18 is 54 (-7/27) = (-7/27) × (2/2) = (-14/54) (11/18) = (11/18) × (3/3) = (33/54) (-7/27) + (11/18) = (-14 + 33)/54 = (19/54) (iv) Given (31/-4) and (-5/8) LCM of -4 and 8 is 8 (31/-4) = (31/-4) × (2/2) = (62/-8) (31/-4) + (-5/8) = (-62 - 5)/8 = (-67/8) 3. Simplify: (i) (8/9) + (-11/6) (ii) (-5/16) + (7/24) Page 3 Exercise 5.1 Page No: 5.4 1. Add the following rational numbers: (i) (-5/7) and (3/7) (ii) (-15/4) and (7/4) (iii) (-8/11) and (-4/11) (iv) (6/13) and (-9/13) Solution: (i) Given (-5/7) and (3/7) = (-5/7) + (3/7) Here denominators are same so add the numerator = ((-5+3)/7) = (-2/7) (ii) Given (-15/4) and (7/4) = (-15/4) + (7/4) Here denominators are same so add the numerator = ((-15 + 7)/4) = (-8/4) On simplifying = -2 (iii) Given (-8/11) and (-4/11) = (-8/11) + (-4/11) Here denominators are same so add the numerator = (-8 + (-4))/11 = (-12/11) (iv) Given (6/13) and (-9/13) = (6/13) + (-9/13) Here denominators are same so add the numerator = (6 + (-9))/13 = (-3/13) 2. Add the following rational numbers: (i) (3/4) and (-3/5) (ii) -3 and (3/5) (iii) (-7/27) and (11/18) (iv) (31/-4) and (-5/8) Solution: (i) Given (3/4) and (-3/5) If p/q and r/s are two rational numbers such that q and s do not have a common factor other than one, then (p/q) + (r/s) = (p × s + r × q)/ (q × s) (3/4) + (-3/5) = (3 × 5 + (-3) × 4)/ (4 × 5) = (15 – 12)/ 20 = (3/20) (ii) Given -3 and (3/5) If p/q and r/s are two rational numbers such that q and s do not have a common factor other than one, then (p/q) + (r/s) = (p × s + r × q)/ (q × s) (-3/1) + (3/5) = (-3 × 5 + 3 × 1)/ (1 × 5) = (-15 + 3)/ 5 = (-12/5) (iii) Given (-7/27) and (11/18) LCM of 27 and 18 is 54 (-7/27) = (-7/27) × (2/2) = (-14/54) (11/18) = (11/18) × (3/3) = (33/54) (-7/27) + (11/18) = (-14 + 33)/54 = (19/54) (iv) Given (31/-4) and (-5/8) LCM of -4 and 8 is 8 (31/-4) = (31/-4) × (2/2) = (62/-8) (31/-4) + (-5/8) = (-62 - 5)/8 = (-67/8) 3. Simplify: (i) (8/9) + (-11/6) (ii) (-5/16) + (7/24) (iii) (1/-12) + (2/-15) (iv) (-8/19) + (-4/57) Solution: (i) Given (8/9) + (-11/6) The LCM of 9 and 6 is 18 (8/9) = (8/9) × (2/2) = (16/18) (-11/6) = (-11/6) × (3/3) = (-33/18) = (16 – 33)/18 = (-17/18) (ii) Given (-5/16) + (7/24) The LCM of 16 and 24 is 48 Now (-5/16) = (-5/16) × (3/3) = (-15/48) Consider (7/24) = (7/24) × (2/2) = (14/48) (-5/16) + (7/24) = (-15/48) + (14/48) = (14 – 15) /48 = (-1/48) (iii) Given (1/-12) + (2/-15) The LCM of 12 and 15 is 60 Consider (-1/12) = (-1/12) × (5/5) = (-5/60) Now (2/-15) = (-2/15) × (4/4) = (-8/60) (1/-12) + (2/-15) = (-5/60) + (-8/60) = (-5 – 8)/60 = (-13/60) (iv) Given (-8/19) + (-4/57) The LCM of 19 and 57 is 57 Consider (-8/57) = (-8/57) × (3/3) = (-24/57) (-8/19) + (-4/57) = (-24/57) + (-4/57) = (-24 – 4)/57 = (-28/57) 4. Add and express the sum as mixed fraction: (i) (-12/5) + (43/10) (ii) (24/7) + (-11/4) Page 4 Exercise 5.1 Page No: 5.4 1. Add the following rational numbers: (i) (-5/7) and (3/7) (ii) (-15/4) and (7/4) (iii) (-8/11) and (-4/11) (iv) (6/13) and (-9/13) Solution: (i) Given (-5/7) and (3/7) = (-5/7) + (3/7) Here denominators are same so add the numerator = ((-5+3)/7) = (-2/7) (ii) Given (-15/4) and (7/4) = (-15/4) + (7/4) Here denominators are same so add the numerator = ((-15 + 7)/4) = (-8/4) On simplifying = -2 (iii) Given (-8/11) and (-4/11) = (-8/11) + (-4/11) Here denominators are same so add the numerator = (-8 + (-4))/11 = (-12/11) (iv) Given (6/13) and (-9/13) = (6/13) + (-9/13) Here denominators are same so add the numerator = (6 + (-9))/13 = (-3/13) 2. Add the following rational numbers: (i) (3/4) and (-3/5) (ii) -3 and (3/5) (iii) (-7/27) and (11/18) (iv) (31/-4) and (-5/8) Solution: (i) Given (3/4) and (-3/5) If p/q and r/s are two rational numbers such that q and s do not have a common factor other than one, then (p/q) + (r/s) = (p × s + r × q)/ (q × s) (3/4) + (-3/5) = (3 × 5 + (-3) × 4)/ (4 × 5) = (15 – 12)/ 20 = (3/20) (ii) Given -3 and (3/5) If p/q and r/s are two rational numbers such that q and s do not have a common factor other than one, then (p/q) + (r/s) = (p × s + r × q)/ (q × s) (-3/1) + (3/5) = (-3 × 5 + 3 × 1)/ (1 × 5) = (-15 + 3)/ 5 = (-12/5) (iii) Given (-7/27) and (11/18) LCM of 27 and 18 is 54 (-7/27) = (-7/27) × (2/2) = (-14/54) (11/18) = (11/18) × (3/3) = (33/54) (-7/27) + (11/18) = (-14 + 33)/54 = (19/54) (iv) Given (31/-4) and (-5/8) LCM of -4 and 8 is 8 (31/-4) = (31/-4) × (2/2) = (62/-8) (31/-4) + (-5/8) = (-62 - 5)/8 = (-67/8) 3. Simplify: (i) (8/9) + (-11/6) (ii) (-5/16) + (7/24) (iii) (1/-12) + (2/-15) (iv) (-8/19) + (-4/57) Solution: (i) Given (8/9) + (-11/6) The LCM of 9 and 6 is 18 (8/9) = (8/9) × (2/2) = (16/18) (-11/6) = (-11/6) × (3/3) = (-33/18) = (16 – 33)/18 = (-17/18) (ii) Given (-5/16) + (7/24) The LCM of 16 and 24 is 48 Now (-5/16) = (-5/16) × (3/3) = (-15/48) Consider (7/24) = (7/24) × (2/2) = (14/48) (-5/16) + (7/24) = (-15/48) + (14/48) = (14 – 15) /48 = (-1/48) (iii) Given (1/-12) + (2/-15) The LCM of 12 and 15 is 60 Consider (-1/12) = (-1/12) × (5/5) = (-5/60) Now (2/-15) = (-2/15) × (4/4) = (-8/60) (1/-12) + (2/-15) = (-5/60) + (-8/60) = (-5 – 8)/60 = (-13/60) (iv) Given (-8/19) + (-4/57) The LCM of 19 and 57 is 57 Consider (-8/57) = (-8/57) × (3/3) = (-24/57) (-8/19) + (-4/57) = (-24/57) + (-4/57) = (-24 – 4)/57 = (-28/57) 4. Add and express the sum as mixed fraction: (i) (-12/5) + (43/10) (ii) (24/7) + (-11/4) (iii) (-31/6) + (-27/8) Solution: (i) Given (-12/5) + (43/10) The LCM of 5 and 10 is 10 Consider (-12/5) = (-12/5) × (2/2) = (-24/10) (-12/5) + (43/10) = (-24/10) + (43/10) = (-24 + 43)/10 = (19/10) Now converting it into mixed fraction = 1 9/10 (ii) Given (24/7) + (-11/4) The LCM of 7 and 4 is 28 Consider (24/7) = (24/7) × (4/4) = (96/28) Again (-11/4) = (-11/4) × (7/7) = (-77/28) (24/7) + (-11/4) = (96/28) + (-77/28) = (96 – 77)/28 = (19/28) (iii) Given (-31/6) + (-27/8) The LCM of 6 and 8 is 24 Consider (-31/6) = (-31/6) × (4/4) = (-124/24) Again (-27/8) = (-27/8) × (3/3) = (-81/24) (-31/6) + (-27/8) = (-124/24) + (-81/24) = (-124 – 81)/24 = (-205/24) Now converting it into mixed fraction = -8 13/24Read More
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