{7x+15y=1,15x+7y=-23

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. {7x+15y=1,15x+7y=-23 x1:4x-3y=8;y=7-5x;2:2x-7y=8,3x-8y-10=0;3:4x-y=-1;4:5x-10y+15 y=-1/2x^2-7x+15/2 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 x+y=3 x+2y=9 3/x+1=y y-x=3 y=2x-3 y-3x=1 2(x+1)-y=6 7x-5y=-9 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 若(x-2)的平方+15y-11=0,求代数式-3(2x-y)-{7x-[6x+2y-(10x-8y 若（x-2）*2+15y-11=0,求-3(2x-y)-{7x-〔6x+2y-（10x-8y）〕 10/x+y+3/x-y=-5 15/x+y-2/x-y=-1（用换元法解此方程组） 7x-3y/5=5x-y/3-x+y/2 x-1/5=y+1/3