因式分解法教案

标签：九年级数学下册教案,九年级数学复习教案,http://www.jiaoshi66.com 因式分解法教案,
    (4)(x-7)(x-5)=0  x1=7,x2=5
    2.x+y=0或x+y-1=0,即x+y=0或x+y=1
    3.设宽为x,则长为35-2x,依题意,得x(35-2x)=150 
    2x2-35x+150=0 
    (2x-15)(x-10)=0,
    x1=7.5,x2=10,
    当宽x1=7.5时,长为35-2x=20,
    当宽x=10时,长为15,
    因a≥20m,两根都满足条件.
    课后教学反思:_______________________________________________________________
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