3x-y=5 6x+5y+7=0

若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组, 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 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 {2x+y/3-2y=0 2(2x+y)-5=7y 解二元一次方程组:{5(x+y)+3(x-y)=2{7(x+y)-3(x-y)=-6 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 联立方程 有的话 (1){x+2y=0,3x+4y=6(2){5x+6y=16,7x-9y=5（3）{9x-11y+1=0,4x-5y-3