50(1+20%)Y+(Y-5)(X-50)=2400+350怎么解

(x-y)平方+5(x-y)-50 (x+5y)(x-7y-1) 4(x+y)^2-20(x+y-1)+5因式分解 1/(x+y)-1/(x-y)=-3/20,2/(x+y)+3/(y-x)=-(1/5)急啊! 方程组：x(y+1)+2(y+1)=y(y-1)x-5(y-1) x（4+y）-y（8-x）=-20x(y+1)+2(y+1)=y(y-1)x-5(y-1) x（4+y）-y（8-x）=-20（这是一个方程组.） x>0,y>0 2x+5y=20 1/x+1/y的最大值 因式分解 -5x³y(x-y)³+20y【x²（y-x）】² (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 (x+y)/6+(x-y)/10=1,(x+y)/6-(x-y)/10=5 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 1/x-1/y=x,求5y+xy-5y/y-xy-x=? 化简求值:(x+y)-(2x+1/2y)-(3x+1/6y)-(4x+1/12y)-(5x+1/20y)-.(10x+1/90y) ,其中x=1,y=-2 绝对值化简|x-y+1|-2|y-x-3|+|y-x|+5y y''-5y'+6y=3x+1通解 x-y+5y-4y 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