若1/x+1/y=5,求3x+4xy+3y/x+3xy+y的值

若1/x+1/y=5,求3x+4xy+3y/x+3xy+y的值 若1/X-1/Y=3,求5X+2XY-5Y/X-4XY-Y 若1/x-1/y=3,求5x+2xy-5y/x-4xy-y的值 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 若（x+1)^2+|y-2|=0,求3x^2-[5xy-(x^2y-3xy)+4x^2y-8xy]的值 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 若(1/x )-(1/y)=3,求(3x+4xy-3y)/(x-2xy-y)的值. 已知x+y=3,xy=1,求代数式5xy+4x+7y+6x-3xy-4xy+3y的值. 已知1/x+1/y=5,求x+y+3xy/2x-4xy+2y的值,已知1/x+1/y=5,x+y+3xy/2x-4xy+2y的值, x-y=1,xy=2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 已知x y=1,xy=-3,求2xy-4x 4(y-2(xy-x)) 已知x-y=3,xy=1,求（-2x+2x+3y)-(3xy+2y-2x)-(x+4y+xy) X+y=3 xy=1求-5x-5y+3xy的值 若x-y=4,xy=-1求(-2xy+3x+4y）-（3xy+9y-2x)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 已知：x-y=1,xy=－2,求(3x－4y+2xy)－(2x－5y+5xy)的值