Question

化简（2-x分之1）+x的平方-2x乘以（x的平方-4）？

Answer 1

1）(2x+2)/x-(x+2)/(x-2)=(x²-2)/(x²-2x)
两边同时乘以x(x-2):
(2x+2)(x-2)-x(x+2)=x²-2
2x²-4x+2x-4-x²-2x=x²-2
-4x=2
x=-1/2
经检验此为原方程的解.
2）由|x-2|+(2x-y-3)²=0得
x-2=0
且2x-y-3=0
得x=2,y=2x-3=1
[1/(x-y)+1/(x+y)]÷[(2x-y)/(x²-y²)]
=[x+y+x-y]÷(2x-y)
=2x÷(2x-y)
=4÷(4-1)
=4/3,7,