1.已知 x=二分之三 求8x³(x-3)+12x²(3-x) 2.求(a-2)²-6(2-a)的值,a=-2

问题描述:

1.已知 x=二分之三 求8x³(x-3)+12x²(3-x) 2.求(a-2)²-6(2-a)的值,a=-2

[1]8x³(x-3)+12x²(3-x)=4x²(x-3)(2x-3)=4x²(x-3)*0=0
[2](a-2)²-6(2-a)=(a-2)(a-2+4)=(a+2)(a-2)=0

8x³(x-3)+12x²(3-x)
=8x³(x-3)-12x²(x-3)
=4x²(x-3)(2x-3)
=4*(2分之3)²*(2分之3-3)(2*2分之3-3)
=4*(2分之3)²*(2分之3-3)(3-3)
=4*(2分之3)²*(2分之3-3)*0
=0
(a-2)²-6(2-a)
=(a-2)²+6(a-2)
=[(a-2)+6](a-2)
=(a+4)(a-2)
=(-2+4)(-2-2)
=2*(-4)
=-8