问题 解答题

分解因式

(1)a2-1+b2-2ab

(2)(x2+1)2-4x2

(3)(x+y)2+6(x+y)+9

(4)x4-5x2+4

答案

(1)a2-1+b2-2ab,

=a2+b2-2ab-1,

=(a-b)2-1,

=(a-b+1)(a-b-1);

(2)(x2+1)2-4x2

=(x2+1+2x)(x2+1-2x),

=(x+1)2(x-1)2

(3)(x+y)2+6(x+y)+9=(x+y+3)2

(4)x4-5x2+4,

=(x2-4)(x2-1),

=(x-1)(x+1)(x-2)(x+2).

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