10、通分x+1/x(x-1)、x/x²-1、2/x²-2x+111、先化简,再求值已知x+y=2,x-y=1/2,求2x²-2y²/x²+2xy+y²的值

Question

10、通分
x+1/x(x-1)、x/x²-1、2/x²-2x+1
11、先化简,再求值
已知x+y=2,x-y=1/2,求2x²-2y²/x²+2xy+y²的值

Answer 1

分母分别为：x(x-1); (x+1)(x-1); (x-1)²
所以,公分母为：x(x+1)(x-1)²
∴通分后分子分别为：(x+1)²(x-1); x²(x+1); 2x(x+1)
11）.2x²-2y²/x²+2xy+y²=2(x+y)(x-y)/(x+y)²=2(x-y)/(x+y)=2*1/2/2=1/2