若(5x+y)(7x+10y)=1/2,则x/y=______;若x+1/x=3,则x^2+1/x^2

若5x+y/7x+10y=1/2,则x/y=? 若7x+10y分之5x+y=1/2,则x/y= 若（5x+y）／(7x+10y)=1/2则x/y= {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 x-y/7 - x+y/10 =1/2 2(x-y)-5(x+y)=3修改、、、、（x-y)/7-(x+y)/10=1/2 2(x-y)-5(x+y)=3 { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 若(5x+y)(7x+10y)=1/2,则x/y=______;若x+1/x=3,则x^2+1/x^2 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若｜y+5｜+(5x+1)2=0,求-3(2x-y)-｛7x-[6x+2y-(10x-8y)]-x-2(3x-4y)｝的值 若|y+5|+(5x+1)^2=0,求代数式-3(2x-y)-{7x-[6x+2y-(10x-8y)]-x-2(3x-4y)}的值 若｜y+5｜+(5x+1)^2=0,求-3(2x-y)-｛7x-[6x+2y-(10x-8y)]-x-2(3x-4y)｝的值 x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 例X=1 y=21.X+Y=5 X-Y=15 2.2X+3Y=4 5X+6Y=7 3.X+3Y=5 3X+Y=-1 4.2X+Y=3 3X+5Y=11 5.4X+3Y=6 2X+Y=4 6.X+Y=180 X=3Y-10 7.3X-2Y=3 2X-Y=7 8.5X+3Y=7Y X+Y=45 9.3X+4Y=126X+8Y=24 X:6Y=1:4 10.X+Y=138 X-45=Y+53 11.X+Y=60 14Y=20X 12.2X+3Y=15.5 5X+6Y=35 13.X+Y=170 3 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 (x+y)/6+(x-y)/10=1,(x+y)/6-(x-y)/10=5 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于