解方程:(x+1)(x+3)(x+5)(x+7)+15=0

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解方程:(x+1)(x+3)(x+5)(x+7)+15=0

解方程:(x+1)(x+3)(x+5)(x+7)+15=0
解方程:(x+1)(x+3)(x+5)(x+7)+15=0

解方程:(x+1)(x+3)(x+5)(x+7)+15=0
[(x+1)(x+7)][(x+3)(x+5)]+15=0
[(x²+8x)+7][(x²+8x)+15]+15=0
(x²+8x)²+22(x²+8x)+105+15=0
(x²+8x)²+22(x²+8x)+120=0
(x²+8x+10)(x²+8x+12)=0
(x²+8x+10)(x+2)(x+6)=0
x=-4-2√6,x=-4+2√6,x=-2,x=-6

x=-2

(x+4-3)(x+4+3)(x+4-1)(x+4+1)+15=0
[(x+4)^2-9][(x-4)^2-1]+15=0
(x+4)^4-10(x+4)^2+24=0
[(x+4)^2-4][(x+4)^2-6]=0
x=-2或-6,x=-4+根号6或-4-根号6

不会嘢,几年级的呀??