If the constant term of the expansion of (x + a) &# 178; (1 / X - 1) ^ 5 is - 1, then the real number a =? A. 1 B.9 C. - 1 or - 9 D.1 or 9

If the constant term of the expansion of (x + a) &# 178; (1 / X - 1) ^ 5 is - 1, then the real number a =? A. 1 B.9 C. - 1 or - 9 D.1 or 9

Expand to x ^ 2 + 2aX + A ^ 2
So the constant term is related to the coefficients of x ^ - 2 and x ^ - 1
X ^ - 2 is C (3,5) * (- 1 / x ^ 2)
X ^ - 1 is C (4,5) * (- 1 / x)
So the constant term should be - 10 + 10a-a ^ 2 = - 1
A = 1 or 9
No problem after two verifications

The sum of coefficients of (4-3x + 2Y) n (n ∈ n *) expansion without y is______ ．

Since (4-3x + 2Y) n (n ∈ n *) expansion does not contain the term of Y, that is, (4-3x + 2Y) n when y index is 0, that is, the terms of (4-3x) n expansion, let x = 1, then the sum of coefficients of (4-3x) n expansion is (4-3) n = 1; therefore, the answer is: 1

In the expansion of (1 + x) ^ m, the coefficient of X ＾ 2 is 45, M =?
The binomial is never

T(r+1)=C(m,r)*1*x^r
Because the coefficient of x ^ 2 is 45
So r = 2
T3=C(m,2)1*x^2=45
So C (m, 2) = 45
m=10
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