题目内容
(1)简便方法计算:98×102-1002
(2)分解因式:a2(x-y)+9(y-x)
(2)分解因式:a2(x-y)+9(y-x)
(1)98×102-1002,
=(100-2)(100+2)-1002,
=1002-4-1002,
=4;
(2)a2(x-y)+9(y-x),
=a2(x-y)-9(x-y),
=(x-y)(a2-9),
=(x-y)(a+3)(a-3).
=(100-2)(100+2)-1002,
=1002-4-1002,
=4;
(2)a2(x-y)+9(y-x),
=a2(x-y)-9(x-y),
=(x-y)(a2-9),
=(x-y)(a+3)(a-3).
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