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请来答
请来答
请来答
(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+7)[(x^2+8x+7)+8]+15
=(x^2+8x+7)^2+8(x^2+8x+7)+15
=[(x^2+8x+7)+3][(x^2+8x+7)+5]
=(x^2+8x+10)(x^2+8x+12)
=(x^2+8x+10)(x+2)(x+6)
（X+2）（X+6）（X*2+8X+10）
（x2+4x+3)(x+5)(x+7)+15
(x3+9x2+23x+15)(x+7)+15
(x4+16x3+86x2+176x+105)+15
x4+16x3+86x2+176x+120
(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
设x^2+8x=y则
原式=（y+7）（y+15）+15=y^2+22y+105+15=y^2+22y+120=(y+10)(y+12)
=(x^2+8x+10)(x^2+8x+15)=(x^2+8x+10)(x+3)(x+5)
原式=[(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+8x+12)
=(x^2+8x+10)(x+2)(x+6)
原式=[(x+1)(x+7)][(x+3)(x+5)]+15
=(x^2+8x+7)(x^2+8x+15)+15
=[(x^2+8x)+7)][(x^2+8x)+15]+15
=(x^2+8x)^2+22(x^2+8x)+120//把x^2+8x当作一个整体
=(x^2+8x+12)(x^2+8x+10)
=(x+2)(x+6)(x^2+8x+10)
注：x^2是x的平方
原式=（x+1）(x+7)(x+3)(x+5)+15=(x^2+8x+7)^2+8(x^2+8x+7)+15
=(x^2+8x+7+3)(x^2+8x+7+5)
=(x^2+8x+10)(x^2+8x+12)
=x^4+16x^3+86x^2+176x+120