已知1\x减1\y等于五,3x加5xy减3y\2y减7xy减2x的值?

已知1\x减1\y等于五,3x加5xy减3y\2y减7xy减2x的值?
已知1\x减1\y等于五,3x加5xy减3y\2y减7xy减2x的值?

已知1\x减1\y等于五,3x加5xy减3y\2y减7xy减2x的值?
(3x+5xy-3y)/(2y-7xy-2x) =(3/y+5-3/x)/(2/x-7-2/y) =[5-3(1/x-1/y)]/[2(1/x-1/y)-7] =(5-15)/(10-7) =-10/3