现化简,再求值:4x²-(x²+1)(2x-3)+(3x-2)(-3x-2)+(2x-1)(3-x)+(x-4)(x+1),其中x=-2
问题描述:
现化简,再求值:4x²-(x²+1)(2x-3)+(3x-2)(-3x-2)+(2x-1)(3-x)+(x-4)(x+1),其中x=-2
答
4x²-(x²+1)(2x-3)+(3x-2)(-3x-2)+(2x-1)(3-x)+(x-4)(x+1)
=4x²-(2x³-3x²+2x-3)-(9x²-4)+(6x-2x²-3+x)+(x²-4x+x-4)
=4x²-2x³+3x²-2x+3-9x²+4+6x-2x²-3+x+x²-3x-4
=-2x³+(4x²+3x²-9x²-2x²+x²)+(6x-2x+x-3x)-4+3+4-3
=-2x³-3x²+2x
=-x(2x²+3x-2)
=2*(2*4-3*2-2)
=2*0
=0