{30(x-2)=48(y+1) {6(y+4)=3(2x-4) 解方程组

1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 {6/x+y+10/x-y=30 6/x+y-10/x-y=-1 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) (x+y)(x-y)+(x-y)^2-(6x^2×y÷2y-2xy^2÷2y)其中x=-3,y=1/3 解二元一次方程组：3(x+y)-4(x-y)=4,x+y/2+x-y/6+1x+y/2+x-y/6+1=1 (x-2y)(x+y)-2x(-2x-3y)+6x(-x-y),其中x=-1,y=2 (x-2y)(x+y)-2x(-2x-3y)+6x(-x-y),其中x=-1,y=2要讲解和答题 （1）x+y=420,30%x+40%y=160×80% （2）x-y/7-x+y/6=1/2,2(x-y)-5(x+y)+1=0,求方程组解嗷嗷嗷! {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 1=x+y 2=20x+30y 5x+y=6 2x-y=1 x-3y=1 x+2y=6 x+y)(x-y)+(x-y)^2-(6x^2y-2xy^2)/2y,其中x=-2,y=1/3 （x+y)(x-y)+(x-y)^2-(6x^2y-2xy^2)/2Y,其中x=-2,y=1/3 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值