若x 〉0,求 y=2-3x-4x^-2 的最大值.答案是2+3*（9）^(1/3)

若2x-3y=0,求5x+4y/3x-2y 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 若x^5+x^4y+x^4+x+y+1=0,且3x+2y=1,求x,y的值 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若|x-1|+|2x+4y|=0,求3x-2y 若x^2-4x+y^2-10y+29=0,求x^2y^2+2x^3y^2+x^4y^2的值 已知7x+5y/2y-x=3/2,且x≠0,求X/x-4y x²-4x-1=0,求(2x-3)²-(x+y)(x-y)-y² 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 1、若x>-1,求y=x+1/x+1的最小值,并求对应的x的值 2、y=x²+4/x(x>0),求y的最小值3、若x>=0,求y=x²+x+2/x+1的最小值4、求y=x(9-3x)的最大值(0 计算(1) (x+y)(-x-y)(x+y)² (2) (-1/3x²y³)³(3) 若x²+3x-2=0,求2x³+6x²-4x+2的值 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) 若根号x+y-3+绝对值xy+x+y-2=0,求x/y+y/x根号x+y-3+绝对值xy+x+y-2=0,求x/y+y/x 若x+y+3=0,求2/3-2x-2y+(-x-y)^2 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 若x^2+y^2-6x+4y+13=0 求x+y 因式分解 若 x^2+4x+y^2-6y+13=0 求y^x