计算:12xy+(3x2-5xy)-2(3xy+2x2).
计算:12xy+(3x2-5xy)-2(3xy+2x2).
先化简再求值2(x2-xy)-3(2x2-3xy)-2[x2-(2x2-xy+y2)],其中x=-1,y=-2.
(8xy-3x2)-5xy-3(xy-2x2+3)
先化简,后求值:4xy-(2x2+5xy-y2)+2(x2+3xy),其中|x+2|+(y−12)
计算:3xy(x2y-xy2+xy)-xy2(2x2-3xy+2x)因式分解
如果M=3x2-2xy-4y2,N=4x2+5xy-y2,则8x2-13xy-15y2等于( )
(2x2-3xy+4y2)+(x2+2xy-3y2)化简(要有过程)
已知x2-xy=3,xy-y2=-5,试求代数式x2+2xy-3y2的值.
已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2的值为( )
已知:x2+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2的值.
已知x2+xy=2,y2+xy=5,则12x2+xy+12y2=___.
已知x2-xy=-3,2xy-y2=-8,求2x2+4xy-3y2的值.