】:(3x+5)(2x-3)-4x(2x-1)+(2x-1)^2,其中x=-3

问题描述:

】:(3x+5)(2x-3)-4x(2x-1)+(2x-1)^2,其中x=-3

把x=-3代入上式,得:
(-9+5)(-6-3)+12(-6-1)+(-6-1)^2
=36-84+49
=1

(3x+5)(2x-3)-4x(2x-1)+(2x-1)^2=(3X+5)(2X-3)-(2X-1){4X-(2X-1)}=(3X-5)(2X-3)-(2X-1)(2X+1)=
6X^X-9X-10X+15-4X^X+1=2X^X-19X+16=18+57+16=91.

(3x+5)(2x-3)-4x(2x-1)+(2x-1)^2
=6x²-9x+10x-15-8x²+4x+4x²-4x+1
=2x²+x-14
x=-3时
原式=2x9-3-14
=1