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Given the equation x ^ 2 + 3x-2 = 0, then the coefficient of quadratic term is 1, and the two equations which are two times of the known equation are?
-b=2*(-3),b=6
c=4*(-2)=-8
So the equation is x ^ 2 + 6x-8 = 0
In the expansion of (1 + x) + (1 + x) ^ 2 + (1 + x) ^ 3 +... + (1 + x) ^ n, the coefficient of term x ^ 4 is
(n+2)C5 ,
X ^ 4 at least from (1 + x) ^ 4, there are coefficients C (4,4) (1 + x) ^ 5, coefficients C (5,4) (1 + x) ^ 6, coefficients C (6,4). (1 + x) ^ n, coefficients C (n, 4) must be added up to be the coefficients of x ^ 4 in the expansion
In the expansion of (1-x) ^ 5 - (1-x) ^ 6, the coefficient of the term with x ^ 3 is
A、-5
B、5
C、-10
D、10
What to choose, why, please write about the process,
C(5,2)(-x)³-C(6,3)(-X)³
therefore
Coefficient = C (6,3) - C (5,2)
=20-10
=10
Choose D
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