已知x²+8x-13=0,求(x+2)(x-2)-4x(x-1)+(2x+1)²的值
问题描述:
已知x²+8x-13=0,求(x+2)(x-2)-4x(x-1)+(2x+1)²的值
答
(x+2)(x-2)-4x(x-1)+(2x+1)2
=x2-4-4x2+4x+4x2+4x+1
=x2+8x-3当x2+8x=13时,原式=13-3=10.лл���ú�ѧϰ�����Ǻ�