Question

9x+6x^2-3(x-2/3)x^2x=2

先化简,再求值
9x+6x^2 -3(x-2/3x^2).其中x=-2
1/4(-4x^2+2x-8)-(1/2x-1),其中x=1/2

Answer 1

9x+6x² -3(x-2/3x²)=9x+6x²-3x+2x²=8x²+6x=8×(-2)²+6×(-2)=32-12=201/4(-4x²+2x-8)-(1/2x-1)=-x²+1/2x-2-1/2x+1=-x²-1=-(1/2)²-1=-1/4-1=-5/4