Assignment-1 Binomial Theorem 1685019641490
Assignment-1 Binomial Theorem 1685019641490
Assignment-1 Binomial Theorem 1685019641490
ASSIGNMENT-1
11 11
2 1 1
1. Find the coefficients : (i) x7 in a x (ii) x7 in ax 2
bx bx
(iii) Find the relation between a & b , so that these coefficients are equal.
2. If the coefficients of (2r + 4)th , (r 2)th terms in the expansion of (1 + x)18 are equal , find r.
3. If the coefficients of the rth, (r + 1)th & (r + 2)th terms in the expansion of (1 + x)14 are in AP, find r.
10 8
x 3 1 1/3 1/5
4. Find the term independent of x in the expansion of (a) 2 (b) x x
3 2 x
2
5. If the coefficients of 2nd, 3rd & 4th terms in the expansion of (1 + x)2n are in AP, show that 2n² 9n + 7 = 0.
6. If a, b, c & d are the coefficients of any four consecutive terms in the expansion of (1 + x)n, n N, prove
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a c 2b
that a b c d b c .
11
7
7. In the expansion of 1 x find the term not containing x.
x
9.
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Prove that the ratio of the coefficient of x10 in (1 x²)10 & the term independent of x in x
x
10
is 1 : 32 .
n 4
10. Let (1+x²)² . (1+x)n = a K . xK . If a1 , a2 & a3 are in AP, find n.
K0
8
2 log 4x 44 1
Find the value of x for which the fourth term in the expansion, 5
5 5
11. is 336.
3 2 x 1 7
5log5
n
r 1 3r 7r 15r
13. Find the sum of the series (1) . nC r 3r 4 r .....up to m terms
r 2r
r0 2 2 2 2
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ANSWERS
11C
a6 11
1C
a5 5
1. (i) (ii) (iii) ab = 1 2. r = 6 3. r = 5 or 9 4. (a) (b) T6 = 7
5
b5 6
b6 12
5
7. 1+ 11
1C
2k . 2kC
k 7k 10. n = 2 or 3 or 4 11. x = 0 or 1 12. nC (3nr
r 2nr)
k1
2 mn
1
13.
2 1 2
n mn
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