已知X²-5X=14,求(X-1)(2X-1)-(X+1)²+1的值
问题描述:
已知X²-5X=14,求(X-1)(2X-1)-(X+1)²+1的值
答
(X-1)(2X-1)-(x+1)2+1=x2-5x=14
答
(x-1)(2x-1)-(x+1)*(x+1)+1
=(2x²-3x+1)-(x²+2x+1)+1
=2x²-3x+1-x²-2x-1+1
=x²-5x+1
因为x²-5x=14
所以原式=14+1
=15
答
(X-1)(2X-1)-(X+1)²+1
=2X^2-3X+1-X^2-2X-1+1
=X^2-5X+1
=14+1
=15