(1+1)^n=32
2^n=32
n=5
(x²-1/x)^5
C(5,a)(x²)^(5-a)(-1/x)^a
=C(5,a)(-1)^a (x)^(10-2a-a)
10-3a=4
a=2
所以
系数=C(5,a)(-1)^a=C(5,2)(-1)^2=5×4÷2=10
(1+1)^n=32
2^n=32
n=5
(x²-1/x)^5
C(5,a)(x²)^(5-a)(-1/x)^a
=C(5,a)(-1)^a (x)^(10-2a-a)
10-3a=4
a=2
所以
系数=C(5,a)(-1)^a=C(5,2)(-1)^2=5×4÷2=10