七年级数学测试卷哪位高手会做啊,我实在不会:帮帮忙啊,很急的:因式分解:( x+1)(x+3)(x+5)(x+7)+15

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七年级数学测试卷哪位高手会做啊,我实在不会:帮帮忙啊,很急的:因式分解:( x+1)(x+3)(x+5)(x+7)+15

七年级数学测试卷哪位高手会做啊,我实在不会:帮帮忙啊,很急的:因式分解:( x+1)(x+3)(x+5)(x+7)+15
七年级数学测试卷
哪位高手会做啊,我实在不会:帮帮忙啊,很急的:
因式分解:( x+1)(x+3)(x+5)(x+7)+15

七年级数学测试卷哪位高手会做啊,我实在不会:帮帮忙啊,很急的:因式分解:( x+1)(x+3)(x+5)(x+7)+15
(x + 1)(x + 3)(x + 5)(x + 7) + 15
= (x + 1)(x + 7)(x + 3)(x + 5) + 15
= (x^2 + 8x + 7)(x^2 + 8x + 15) + 15
= (x^2 + 8x + 11 - 4)(x^2 + 8x + 11 + 4) + 15
= (x^2 + 8x + 11)^2 - 16 + 15
= (x^2 + 8x + 11)^2 - 1
= (x^2 + 8x + 12)(x^2 + 8x + 10)
= (x + 6)(x + 2)(x^2 + 8x + 10)

( x+1)(x+3)(x+5)(x+7)+15
=(X+1)(X+7) * (X+3)(X+5)+15
=(x^2+8X+7)(X^2+8X+15)+15
=(X^2+8x)^2+22(x^2+8x)+120
=(X^2+8x+10)(X^2+8x+12)
=(X^2+8X+10)(X+2)(X+6)

(x+4-3)(x+4+3)(x+4-1)(x+4+1)+15
=((x+4)^2-9)((x+4)^2-1)+15
=((x+4)^2-5-4)((x+4)^2-5+4)+15
=((x+4)^2-5)^2-16+15
=((x+4)^2-5)^2-1