1/2x+1/4y=70,x,y各多少

已知方程式4x+y=5 3x+2y=1 求x y各等于多少? {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 已知4x=9y求(1)x+y/y (2)y-x/2x 1.已知x/x-1=（y²+4y-1）/（y²+4y-2）,则y²+4y-x的值为多少? 1/2X-1/X+Y*(X+Y/2X-X-Y)等于多少, 满足方程y^4+2x^4+1=4x^2*y的整数x,y有多少对? x(y-1)-y(x-1)=4,则2分之x的平方加y的平方=多少 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 设实数X,Y满足X^2+Y^2=1,则3X+4Y的最大值为多少 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y 1、x(x-y)(x+y)-x(x+y)^2