x/3+y/4>=2√(xy/12),这是基本不等式怎么解,最后等于xy题是这样的：已知x,y属于R*，且满足x/3+y/4=1，则xy的最大值为。这是一道基本不等式题

因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) （-3x^y+2xy)-( )=4x^+xy （12x^2y-8xy^2+16xy）/-3x+2y-4=? (12x^2y-8xy^2+16xy）/-3x+2y-4=? 当x-y=2xy时,求4x-3xy-4y/xy X×X-2XY-Y×Y+2X-2Y+2=02X×2X-4XY-2Y×2Y+3X-3Y+4=0X×X+2XY+Y×Y+X+Y-56=0X×X-2XY+Y×Y-X+Y-12=0X×X-3XY+Y×Y=-13X×3X-XY+3Y×3Y=13 两个在一起的方程之间有所联系（要求一步一步写出来） 已知X+Y=3,XY=-1,求2(X-Y)^4-9(X-Y)^2+12XY 若x+y=4,x^3+y^3=(x+y)(x^2-xy+y^2)z,求x^3+12xy+y^3的值. 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 已知x-y=4xy,求2x+3xy-2y/x-2xy-y的值 x-y=4xy,试求2x+3xy-2y/x-2xy-y 已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值! x-y=4xy,试求2x+3xy-2y/x-2xy-y 已知x-y=3xy,求5x+2xy-5y/x-4xy-y的值 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1