先化简再求值:(3x+4)(3x-4)-5x(x-1)-(2x-1)²其中x=-1/3

问题描述:

先化简再求值:(3x+4)(3x-4)-5x(x-1)-(2x-1)²
其中x=-1/3

原式=9x²-16-5x²+5x-4x²+4x-1
=9x-17
=-20

(3x+4)(3x-4)-5x(x-1)-(2x-1)²
= 9x²-16-5x²+5x-4x²+4x-1
=9x-17
=9×﹙-1/3﹚-17
=-20