化简求值:已知x²-2x=2,求代数式(x-1)²+(x+3)(x-3)+(x-3)(x-1)的值
问题描述:
化简求值:已知x²-2x=2,求代数式(x-1)²+(x+3)(x-3)+(x-3)(x-1)的值
答
∵x²-2x=2∴x²-2x+1=3即(x-1)²=3原式=(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+1) =(x-1)²+2(x²-2x-3) =3+2×(-1) ...