求6xy+7y+[8x-(5xy-y+6x)]的值,其中x+4y=1,xy=5.

x+y=8,xy=-2,求(5xy+4x+7y)+(6x-3xy)-(4xy-3y)的值 已知(1/x)-(1/y)=5,求(6x+7xy-6y)/(8y-9xy-8y) x+y=6,xy=8,求5x+xy+5y/x-xy+y的值 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 3(x-y)²-7(x-y)+8(x-y)²+6(x-y)求详细过程（2） 5xy-4x²y-8xy²+3xy-xy²+4x²y 已知A=8x^2y-6xy^2-3xy,B=7xy^2-2xy+5x^2y求A-B 已知x+4y=-1,xy=5,求（6xy+7y）+【8x-（5xy-y+6x）】的值 化简求值：已知x+4y=-1,xy=5,求（6xy+7y）+【8x-（5xy-y+6x）】的值 已知x+4y= ﹣1,xy=5 ,求代数式（6xy+7y)+[8x-(5xy-y+6x)]的值. 化简求值：已知x+4y=-1,xy=5,求（6xy+7y）+【8x-（5xy-y+6x）】的值 已知x+4y=-1.xy=5.求代数式（6xy+7y）+[8x-（5xy-y＋6x）]的值, 求6xy+7y+[8x-(5xy-y+6x)]的值,其中x+4y=1,xy=5. 已知X+Y=6,xy=3求代数式（5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)的值 x-y=3,xy=5,求代数式（7xy+4x-7y）+(6x-3xy)-(3y+4xy)的值快 已知x+y=3,xy=1,求代数式5xy+4x+7y+6x-3xy-4xy+3y的值. 已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 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xy^2=-6,求-xy(x^3y^7-3x^2y^5-y）的值