2x/x+y+2y/x+y
=(2x+2y)/(x+y)
=2;
a/a+b+b/a-b
=(a(a-b)+b(a+b))/(a²-b²)
=(a²+b²)/(a²-b²)
1/3x²+2/4y-5/6xy
题目有问题
如果本题有什么不明白可以追问,