已知x方-5x=14,求(x-1)(2x-1)-(x+1)方+1的值
问题描述:
已知x方-5x=14,求(x-1)(2x-1)-(x+1)方+1的值
答
x方-5x=14x方-5x-14 = 0(x+2)(x-7) = 0x = -2,或x = 7x = -2时:(x-1)(2x-1)-(x+1)方+1 = -3*(-5)-(-1)方+1 = 15-1+1 = 15x = 7时:(x-1)(2x-1)-(x+1)方+1 = 6*13-(-7)方+1 = 78-49+1 = 30...