已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值

问题描述:

已知x方-3x=4,求2(x-1)方-(x+1)(x-2)-3的值

x²-3x=4
2(x-1)方-(x+1)(x-2)-3
=2x²-4x+2-x²+x+2-3
=x²-3x+1
=4+1
=5