先化简再求值:4x³-[-x²+3(x³-1/3x²)],其中x=-3

问题描述:

先化简再求值:4x³-[-x²+3(x³-1/3x²)],其中x=-3

4x³-[-x²+3(x³-1/3x²)]=4x^3+x^2-3x^3+x^2=x^3+2x^2
将x=-3代入可得:x^3+2x^2=-9
所以4x³-[-x²+3(x³-1/3x²)]=-9