1.若x+y= -6,xy=2.75,则x-y=?2.若x²+mx-15=(x+3)(x+n),则m的值为几?3.(2+1)(2²+1)(2^4+1）.（2^2n)的值为多少?

若x-y=5,xy=6,则xy-xy是多少 若x+y=6,xy=2.75,x-y>0,求x-y的值 若x>0,y>0,且x-根号xy=6y,则x/y= 若x+y分之xy=2,则-x+3xy-y分之3x-xy+3y=多少? 若xy/x+y=2,则3x-5xy+3y/-x+3xy-y=?/是分之 若x+y分之xy=2,则-x+3xy-y分之3x-xy+3y=多少? 若xy/x+y=2,则3x-xy+3y/-x+3xy-y= 若|x|/y+y/|y|=0,则|xy|/xy=?是：若|x|/x+y/|y|=0，则|xy|/xy=？ |x|/x+y/|y|+xy/|xy|= 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y) 若xy/(x+y)=3,则(6x+4xy+6y)/(9x+4xy+9y)=______ 若x-y=5,xy=6,求x^2-xy^2和x^2y+xy^2 若以只x+y=﹣5,xy=6,则x²－xy+y²=? 若x-y=5,xy=6,则x方y+xy方=一道初一数学题 若x-y=5,xy=6,则x的平方y-xy的平方的值是? 若x²-6xy+8y²=0（XY≠0）则x：y= 若x-y=5,xy=6,则x²y-xy²的值为