整 式 的 加 减复习例例1.1.求整式求整式x x2 2-7x-2-7x-2与与-2x-2x2 2+4x-1+4x-1的差。的差。解：由题意得解：由题意得(x(x2 2-7x-2)-(-2x-7x-2)-(-2x2 2+4x-1)+4x-1)=x=x2 2-7x-7x 2 2+2x2x2 2 -4x 4x+1 1=3x=3x2 2-11x-1-11x-1 2.2.计算：计算：-2y-2y3 3+(3xy+(3xy2 2-x-x2 2y)-2(xyy)-2(xy2 2-y y3 3).).(1)(1)求求2x2x2 2y y3 3,-4x,-4x2 2y y3 3,-3x,-3x2 2y y3 3的和的和 (2)(8xy-3y(2)(8xy-3y2 2)-5xy-2(3xy-2x)-5xy-2(3xy-2x2 2)练一练练一练例例3 3 化简求值化简求值:2x:2x2 2y-3xyy-3xy2 2+4x+4x2 2y-5xyy-5xy2 2,其中其中x=1,y=-1x=1,y=-1解：解：2x2x2 2y-3xyy-3xy2 2+4x+4x2 2y-5xyy-5xy2 2 =(2x=(
