已知x²-3x=14,求(x-1)(2x-1)-(x+1)²-2(2-x)的值
问题描述:
已知x²-3x=14,求(x-1)(2x-1)-(x+1)²-2(2-x)的值
答
(x-1)(2x-1)-(x+1)²-2(2-x)
=2x²-3x+1-(x²+2x+1)-4+2x
=x²-3x
=14
答
(x-1)(2x-1)-(x+1)²-2(2-x)
=2x^2-x-2x+1-(x^2+2x+1)-4+2x
=2x^2-3x+1-x^2-2x-1-4+2x
=x^2-3x-4=14 -4=10