ahb0
春芽
共回答了9个问题采纳率:100% 举报
1.
(1/2m)-[1/(m+n)]*{[(m+n)/2m]-m-n}
=(1/2m)-[(m+n)/(2m²+n)]+[m/(m+n)]+[n/
(m+n)]
=(4m²+3n)/(2m²+n)
2.
{(2/xy)÷[(1/x)+(1/y)]+x²+2xy+y²}*[(2x)/
(x-y)]
={(2/xy)÷[(y/xy)+(x/xy)]+x²+2xy+y²}*
[(2x)/(x-y)]
=[(2/x+y)+(x+y)²]*[-(2/x+y)]
=[2(x+y)²]/(x+y)
=-[(4x²+8x+4y²)/(x+y)]
=-[(2x+2y)²/(x+y)]
1年前
9