已知x的平方-2x=2,求(x-1)的平方+(x+3)(x-3)+(x-3)(x-1)得值
问题描述:
已知x的平方-2x=2,求(x-1)的平方+(x+3)(x-3)+(x-3)(x-1)得值
答
x²-2x=2
(x-1)²=3
(x-1)²+(x+3)(x-3)+(x-3)(x-1)
=3+x²-9+x²-4x+3
=2x²-4x-3
=2(x²-2x+1)-5
=2(x-1)²-5
=2*3-5
=1