先化简,在求值:x(x+2)-(x+1)(x-1),其中x=-1/2

x(x+2)-(x+1)(x-1),
=(x²+2x)-(x²-1²)
=x²+2x-x²+1
=2x+1
=2*(-1/2)+1
=-1+1
=0

x(x+2)-(x+1)(x-1)
=x方+2x-x方+1
=2x+1
把x=-1/2代入得0
楼主不好意思，你先前出了个化简求值题。由于我粗心，算错了。应该得3 不好意思呀

x(x+2)-(x+1)(x-1)
=x^2+2x-(x^2-1)
=2x+1
原式=2*(-1/2)+1=0

x(x+2)-(x+1)(x-1),
=(x²+2x)-(x²-1²)
=x²+2x-x²+1
=2x+1
=2*(-1/2)+1
=-1+1
=0

答案详细正确