`(x+2)(x+3)(x+4)(x+5)-8`
`=[(x+2)(x+5)][(x+3)(x+4)]-8`
`=(x^2 +7x+10)(x^2 +7x+12)-8`
`=(x^2 +7x+10)^2 +2(x^2 +7x+10)-8`
`=(x^2 +7x+10)^2 +4(x^2 +7x+10)-2(x^2 +7x+10)-8`
`=(x^2 +7x+10)(x^2 +7x+10+4)-2(x^2 +7x+10+4)`
`=(x^2 +7x+10-2)(x^2 +7x+10+4)`
`=(x^2 +7x+8)(x^2 +7x+14)`
\(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-8\)
\(=\left(x^2+7x\right)^2+22\left(x^2+7x\right)+112\)
\(=\left(x^2+7x+8\right)\left(x^2+7x+14\right)\)