x+y分之x-y=2 求x+y分之3x-3y -x-y分之2(x+y)的值
问题描述:
x+y分之x-y=2 求x+y分之3x-3y -x-y分之2(x+y)的值
x-y 3x-3y 2(x+y)
已知 ---- =2 求:----- - ------- 的值.
x+y x+y x-y
答
x+y分之x-y=2
x-y=2(x+y)
求x+y分之3x-3y
=(x+y)分之3(x-y)
=(x+y)分之6(x-y)
=6
-x-y分之2(x+y)
=-(x+y)分之2(x+y)
=-2