己知4x^2+20xy=-25y^2+12x+30y-9,求「（x+2y）（x-2y）-（x+4y）^2」/4y

己知x平方+3xy一4y平方=0(y≠0)求代数式(1)y分之x(2)x+y分之x一y 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知y-2x=10，求[2y（x-y）-（x-y）2+（x+y）2-2xy]÷4y的值． 已知（x+2）^2+|x+y+5|=0,求3x^2y-[2x^2y-(2xy-x^2y)-4x^2]-xy 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* 已知：3x方+xy-2y方=0,求（x+y/x-y + 4xy/y方-x方）除以 x方+2xy-3y方 / x方-9y方 已知；x+y=4,x-y的绝对值=6,求xy(y的平方+y)-y的平方（xy+2x）-3xy 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)} 已知2x+y=0,求x-2y/x²+xy*(x²-y²）/x²-4xy+4y&# 若|x+2y-1|+y²+4y+4=0,求（2x-y）²-2（2x-y)(x+2y)+(x+2y)& 1/x-1/y=4,求分式（3x+xy-3y）/(x-2xy-y)