若2x+y-4=0,求9^x*27^y的值谢谢各位啦

若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 若／X+Y-9／+（2X-Y+3)=0求X与Y的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 若x y满足x^2+y^2-2x+4y=0求x-2y的最大值 若实数x,y满足x²+y²-2x+4y=0,求x-y的最大值 RT,若（√2x-y）+y^2+4y+4=0,求[(x-y)^2+(x+y)(x-y)]÷2x的值 已知x,y满足{3x-y=9 {x-3y=0 求x+2y+ 4y的平方/x-2y -4x的平方y/x的平方-4y的平方 若3^x=4,3^y=6,求9^2x-y+27^x-y的值. 若2x-y=0,求代数式[(x^2+y^2)-(x-y)^2+2y×(x-y)]÷4y的值 若x,y为正整数,且x^2+y^2-4y-96=0,求x、y的值 若x^2-4x+y^2-10y+29=0,求x^2y^2+2x^3y^2+x^4y^2的值 若x*x+4*y*y+2*x-4*y+2=0,求5*x*x+16*y*y的算术平方跟 若实数x、y满足x*x+y*y-2x+4y+5=0,求x-y的值 若(x+y)(x+y-1)-2=0,求x+y的值求 若3x^2+xy-2y^2=0,求（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)的值 若x^2-4x+4+y^2-2/3y+2/9=0求x+1/y及x^2+1/y^2的值 若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值.