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KVPY
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Contents
KVPY MATHEMATICS
01. NUMBER SYSTEM 1
02. ALGEBRA 3
03. TRIGONOMETRY 10
04. INEQUALITIES 12
05. GEOMETRY 14
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M a thema tics
M a thema tics
Stream : SA
KVPY
h
a pter
Contents
KVPY MATHEMATICS
01. NUMBER SYSTEM 1
02. ALGEBRA 3
03. TRIGONOMETRY 10
04. INEQUALITIES 12
05. GEOMETRY 14
node05\B0B0-BA\KVPY\KVPY Maths Module\01-Maths [Th].P65
Mathematics ????? 1
E
For integers a, b, c
(i) If a | b then a | b c.
(ii) If. a | b and b | c then a | c.
(iii) If a, b are natural numbers and if a | b and b | a, then a = b
(iv) If a | b and a | c then a | (b p + c q) for all integral values of p and q.
b | a means b is a factor of a (or a is a multiple of b).
Number of divisors of a natural number
If N =
3 12k
n nnn
123k
p p p .......p then the number of divisors of N, d(N) = (n
1
+1) (n
2
+1) (n
3
+1)..... (n
k
+1)
Sum of divisors of a natural number? (N)
?(
1 2k
n 1 n 1 n1
1 2k
1 2k
1 p 1p 1p
N ..........
1 p 1p 1p
* **
,,,
?<
,,,
Product of divisors of N
Product of divisors of N =
1 2k
1
(n 1)(n 1).......( n 1)
2
N
* **
[d(N) divisors of N can be grouped in to
1
2
d(N) pairs such that product of each pair is equal to n.]
Perfect number
A natural number N is said to be perfect if sum of all divisors of N, ?(N) = 2N
Eg:– (i) 28 is a perfect number.
1 + 2 + 4 + 7 + 14 + 28 = 56 = 2 × 28
(ii) 496 is a perfect number.
496 = 2
4
× 31
? (
52
12 131
496 992 2 496
1 2 1 31
,,
? < = < <=
,,
Sum of the reciprocals of divisors of a perfect number
Let d
1
, d
2
, d
3
,......, d
n
be all divisors of the perfect number N[including 1 and N].
12n
123n
d d .......... d 1 1 1 1 2N
........ 2
ddd d NN
***
*** * < < <
[L.C.M. of d
1
, d
2
, d
3
,.........., d
n
= N and d
1
+ d
2
+ d
3
+........ + d
n
= 2N]
Sum of reciprocals of factors of 28
1 1 1 1 1 1 28 14 7 4 2 1 56
2
1 2 4 7 14 28 28 28
* * * **
** ** * < < <
Amicable numbers
Two numbers are said to be amicable if the sum of the divisors of one, excluding itself is equal to the other.
220 and 284 are amicable numbers.
220 = 1 + 2 + 4 + 7 1 +142
284 = 1 + 2 + 4 + 5 + 10 + 11 + 20 + 22 + 44 + 55 + 110
Sum of divisors of 220 (excluding 220) is 284 and Sum of divisors of 284(excluding 284) is 220.
CHAPTER # 01 NUMBER SYSTEM
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M a thema tics
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KVPY
h
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Contents
KVPY MATHEMATICS
01. NUMBER SYSTEM 1
02. ALGEBRA 3
03. TRIGONOMETRY 10
04. INEQUALITIES 12
05. GEOMETRY 14
node05\B0B0-BA\KVPY\KVPY Maths Module\01-Maths [Th].P65
Mathematics ????? 1
E
For integers a, b, c
(i) If a | b then a | b c.
(ii) If. a | b and b | c then a | c.
(iii) If a, b are natural numbers and if a | b and b | a, then a = b
(iv) If a | b and a | c then a | (b p + c q) for all integral values of p and q.
b | a means b is a factor of a (or a is a multiple of b).
Number of divisors of a natural number
If N =
3 12k
n nnn
123k
p p p .......p then the number of divisors of N, d(N) = (n
1
+1) (n
2
+1) (n
3
+1)..... (n
k
+1)
Sum of divisors of a natural number? (N)
?(
1 2k
n 1 n 1 n1
1 2k
1 2k
1 p 1p 1p
N ..........
1 p 1p 1p
* **
,,,
?<
,,,
Product of divisors of N
Product of divisors of N =
1 2k
1
(n 1)(n 1).......( n 1)
2
N
* **
[d(N) divisors of N can be grouped in to
1
2
d(N) pairs such that product of each pair is equal to n.]
Perfect number
A natural number N is said to be perfect if sum of all divisors of N, ?(N) = 2N
Eg:– (i) 28 is a perfect number.
1 + 2 + 4 + 7 + 14 + 28 = 56 = 2 × 28
(ii) 496 is a perfect number.
496 = 2
4
× 31
? (
52
12 131
496 992 2 496
1 2 1 31
,,
? < = < <=
,,
Sum of the reciprocals of divisors of a perfect number
Let d
1
, d
2
, d
3
,......, d
n
be all divisors of the perfect number N[including 1 and N].
12n
123n
d d .......... d 1 1 1 1 2N
........ 2
ddd d NN
***
*** * < < <
[L.C.M. of d
1
, d
2
, d
3
,.........., d
n
= N and d
1
+ d
2
+ d
3
+........ + d
n
= 2N]
Sum of reciprocals of factors of 28
1 1 1 1 1 1 28 14 7 4 2 1 56
2
1 2 4 7 14 28 28 28
* * * **
** ** * < < <
Amicable numbers
Two numbers are said to be amicable if the sum of the divisors of one, excluding itself is equal to the other.
220 and 284 are amicable numbers.
220 = 1 + 2 + 4 + 7 1 +142
284 = 1 + 2 + 4 + 5 + 10 + 11 + 20 + 22 + 44 + 55 + 110
Sum of divisors of 220 (excluding 220) is 284 and Sum of divisors of 284(excluding 284) is 220.
CHAPTER # 01 NUMBER SYSTEM
node05\B0B0-BA\KVPY\KVPY Maths Module\01-Maths [Th].P65
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Highest power of a prime number p contained in N!
The highest power of a prime number p contained in N ! = 23
N NN
.........
p pp
? ?? ?? ?
* **
? ?? ?? ?
? ?? ?? ?
Cube Root:
3
c b a *
=
3
c b,
+
c
= x + y , where x
3
+ 3xy = a
Note: 1) Above formula can be applied only if x
3
+ 3xy = a
2)
3
y ) y x 3 ( x ) y 3 x ( * * * = y x *
Important Results:
(1)
3 3
b a
1
*
=
2/3 1/3 2/3
a (ab)b
ab
,*
*
(2)
3 3
b a
1
,
=
2/3 1/3 2/3
a (ab)b
ab
**
,
(3) If
k x
2
) b a (
,
*
+
k x
2
) b a (
,
,
= 2a and a
2
– b = 1, then x
2
– k = ± 1
(4) If
k x
2
) b a (
,
*
+
k x
2
) b a (
,
,
= 2(a
2
+ b), then 1
2
k x
2
° <
,
(5)
/ * * * ...... a a a
=
2
1 a 4 1 * *
(a > 0)
(6)
/ , , , ...... a a a
=
2
1 1 a 4 , *
(a > 0)
(7)
/ ....... a a a
= a
(8) times n ....... a a a =
n
n
2
1 2
a
,
Greatest integer function :
(a) [x] represents the greatest integer less than or equal to x.
f(x) = [x] is called the greatest integer function.
(b) {x} is fractional part of x and is defined as {x} = x – [x].
Properties of Greatest integer function :
(a) [x]' x < [x] + 1 and x –1 < [x]' x, 0' x (b) If x? 0, [x] = 1p ix ''
?
(c) [x + m] = [x] + m, if m is an integer. (d) [x] + [y] ' [x + y]' [x] + [y] + 1
(e) [x] + [–x] = 0, if x is an integer and –1 other wise.
(f) The number of positive integers less than or equal to n and divisible by m is given by
n
m
?)
??
??
(g) If p is prime number and e is the largest exponent of p such that p
e
/n! then i
i1
n
e
p
/
<
??
<
??
??
?
(h) The number of zeroes at the end of n! is given by the least of the Highest powers of 2 and 5.
Page 5
M a thema tics
M a thema tics
Stream : SA
KVPY
h
a pter
Contents
KVPY MATHEMATICS
01. NUMBER SYSTEM 1
02. ALGEBRA 3
03. TRIGONOMETRY 10
04. INEQUALITIES 12
05. GEOMETRY 14
node05\B0B0-BA\KVPY\KVPY Maths Module\01-Maths [Th].P65
Mathematics ????? 1
E
For integers a, b, c
(i) If a | b then a | b c.
(ii) If. a | b and b | c then a | c.
(iii) If a, b are natural numbers and if a | b and b | a, then a = b
(iv) If a | b and a | c then a | (b p + c q) for all integral values of p and q.
b | a means b is a factor of a (or a is a multiple of b).
Number of divisors of a natural number
If N =
3 12k
n nnn
123k
p p p .......p then the number of divisors of N, d(N) = (n
1
+1) (n
2
+1) (n
3
+1)..... (n
k
+1)
Sum of divisors of a natural number? (N)
?(
1 2k
n 1 n 1 n1
1 2k
1 2k
1 p 1p 1p
N ..........
1 p 1p 1p
* **
,,,
?<
,,,
Product of divisors of N
Product of divisors of N =
1 2k
1
(n 1)(n 1).......( n 1)
2
N
* **
[d(N) divisors of N can be grouped in to
1
2
d(N) pairs such that product of each pair is equal to n.]
Perfect number
A natural number N is said to be perfect if sum of all divisors of N, ?(N) = 2N
Eg:– (i) 28 is a perfect number.
1 + 2 + 4 + 7 + 14 + 28 = 56 = 2 × 28
(ii) 496 is a perfect number.
496 = 2
4
× 31
? (
52
12 131
496 992 2 496
1 2 1 31
,,
? < = < <=
,,
Sum of the reciprocals of divisors of a perfect number
Let d
1
, d
2
, d
3
,......, d
n
be all divisors of the perfect number N[including 1 and N].
12n
123n
d d .......... d 1 1 1 1 2N
........ 2
ddd d NN
***
*** * < < <
[L.C.M. of d
1
, d
2
, d
3
,.........., d
n
= N and d
1
+ d
2
+ d
3
+........ + d
n
= 2N]
Sum of reciprocals of factors of 28
1 1 1 1 1 1 28 14 7 4 2 1 56
2
1 2 4 7 14 28 28 28
* * * **
** ** * < < <
Amicable numbers
Two numbers are said to be amicable if the sum of the divisors of one, excluding itself is equal to the other.
220 and 284 are amicable numbers.
220 = 1 + 2 + 4 + 7 1 +142
284 = 1 + 2 + 4 + 5 + 10 + 11 + 20 + 22 + 44 + 55 + 110
Sum of divisors of 220 (excluding 220) is 284 and Sum of divisors of 284(excluding 284) is 220.
CHAPTER # 01 NUMBER SYSTEM
node05\B0B0-BA\KVPY\KVPY Maths Module\01-Maths [Th].P65
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KVPY ?????
E
Highest power of a prime number p contained in N!
The highest power of a prime number p contained in N ! = 23
N NN
.........
p pp
? ?? ?? ?
* **
? ?? ?? ?
? ?? ?? ?
Cube Root:
3
c b a *
=
3
c b,
+
c
= x + y , where x
3
+ 3xy = a
Note: 1) Above formula can be applied only if x
3
+ 3xy = a
2)
3
y ) y x 3 ( x ) y 3 x ( * * * = y x *
Important Results:
(1)
3 3
b a
1
*
=
2/3 1/3 2/3
a (ab)b
ab
,*
*
(2)
3 3
b a
1
,
=
2/3 1/3 2/3
a (ab)b
ab
**
,
(3) If
k x
2
) b a (
,
*
+
k x
2
) b a (
,
,
= 2a and a
2
– b = 1, then x
2
– k = ± 1
(4) If
k x
2
) b a (
,
*
+
k x
2
) b a (
,
,
= 2(a
2
+ b), then 1
2
k x
2
° <
,
(5)
/ * * * ...... a a a
=
2
1 a 4 1 * *
(a > 0)
(6)
/ , , , ...... a a a
=
2
1 1 a 4 , *
(a > 0)
(7)
/ ....... a a a
= a
(8) times n ....... a a a =
n
n
2
1 2
a
,
Greatest integer function :
(a) [x] represents the greatest integer less than or equal to x.
f(x) = [x] is called the greatest integer function.
(b) {x} is fractional part of x and is defined as {x} = x – [x].
Properties of Greatest integer function :
(a) [x]' x < [x] + 1 and x –1 < [x]' x, 0' x (b) If x? 0, [x] = 1p ix ''
?
(c) [x + m] = [x] + m, if m is an integer. (d) [x] + [y] ' [x + y]' [x] + [y] + 1
(e) [x] + [–x] = 0, if x is an integer and –1 other wise.
(f) The number of positive integers less than or equal to n and divisible by m is given by
n
m
?)
??
??
(g) If p is prime number and e is the largest exponent of p such that p
e
/n! then i
i1
n
e
p
/
<
??
<
??
??
?
(h) The number of zeroes at the end of n! is given by the least of the Highest powers of 2 and 5.
node05\B0B0-BA\KVPY\KVPY Maths Module\01-Maths [Th].P65
Mathematics ????? 3
E
Number of functions from A to B:
Let n(A) = m and n(B) = n. Under a function f, an element of A can be associated to any of the
n elements of the set B.
i.e., each element of A can be associated to an element of B in n ways.
And A contains m elements.
Therefore total number of functions from A to B =
m
m times
n n n ...... n n === = <
033 31333 2
NOTE : Number of functions from A to A = [n(A)]
n(A)
Finding remainders when divisor is of second or third degree.
Remainder is always one degree less than divisor.
If the divisor is linear expression of the form (ax + b), the remainder is a numerical number i.e. a constant.
But when the divisor is of second degree like (x – a)(x – b) or third degree like (x – a)(x – b) (x – c)
the remainders will be (px + q) or (px
2
+ qx + r) respectively.
In the above cases, the division identity will be
f(x) = (x – a)(x – b)e (x) + (px + q) (or)
f(x) = (x – a)(x – b)(x – c)e (x) + (px
2
+ qx + r)
We can find the value of p, q and r by substituting x = a, x = b and x = c in the above identities. We
shall get equations involving p, q and r.
The values of p, q, r will enable us to write the required remainder.
Using factor theorem the following concepts can be proved.
1. (a
k
+ b
k
) is divisible by (a + b) if k is odd.
2. (a
k
– b
k
) is divisible by (a – b) if k ? N
Many problems can be solved using these two concepts, but they need tactful algebraical manipulation
as can be seen from the following examples.
As per binomial theorem
(1 + x)
n
= 1 +
n
C
1
x
1
+
n
C
2
x
2
+ .....+
n
C
n
x
n
= 1 + nx +
n
C
2
x
2
+ ....+
n
C
n
x
n
(
n
C
1
= n)
This concept is used occasionally in coordination with the concepts given in the above model.
CHAPTER # 02 ALGEBRA
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