已知:x方-2x=2,将下列各式先化简再求值(x-1)方+(x+3)(x-3)+(x-3)(X+1)
问题描述:
已知:x方-2x=2,将下列各式先化简再求值(x-1)方+(x+3)(x-3)+(x-3)(X+1)
答
∵ x方-2x=2
∴(x-1)²=3
(x-1)²+(x+3)(x-3)+(x-3)(X+1)
=(X-1)²+(x-3)(x+3+x+1)
=(x-1)²+2(x-3)((x+2)
=(x-1)²+2(x²-x+6)
=x²+17