整式的加减复习课件.ppt

整式的加减复习新课小结Date复习什么叫同类项?合并同类项的法则?叙述去括号的法则返回*定义所含字母相同,并且同字母的指数也相同口决:同类项,须判断,两相同,是条件合并时,须计算,系数加,两不变同类项:反回复习*去括号法则:括号前面是“+”号,把括号和它前面的“+”号去掉,括号内各项都不变。括号前面是“-”号,把括号和它前面的“-”号去掉,括号里各项都变号。反回复习Date例题例题例2例题例1例题例3返回例题例4Date例1求单项式5x2y,2x2y,2xy2,-4x2y的和(5x2y)+(2x2y)+(-4x2y)+(2xy2)=5x2y·············(去括号)················(合并同类项)新课练习1+2x2y+2xy2-4x2y=5x2y+2x2y+2xy2-4x2y=(5+2-4)x2y+2xy2=3x2y+2xy2解:Date练习1求下列各单项式的和:计算:(1)求2x,5x2,-3x,5x2的和(2)求-4x,2x2,4x,3x2的和返回Date练习1-1答案:解:(2x)+(5x2)+(-3x)+(5x2)=2x+5x2-3x+5x2=5x2+5x2+2x-3x=10x2-x反回练习1*练习1-2解:(-4x)+(2x2)+(4x)+(3x2)=-4x+2x2+4x+3x2=2x2+3x2-4x+4x=5x2答案:反回练习1Date例2求整式2x,-5x2+3x,2x2-1的和:解:新课练习2(2x)+(-5x2+3x)+(2x2-1)=2x-5x2+3x+2x2-1=-5x2+2x2+2x+3x-1=(-5+2)x2+(2+3)x-1=-3x2+5x-1Date