What is the sum of all possible solutions to this equations?
Since $(x+4)^2=|x+4|^2$, so I can ignore the absolute sign of the first term. So we only need to deal with the absolute sign of the second term. This become two cases:
But it turns out my answer is wrong. I am not sure where I did wrong. The correct way is to do a substitution that $u=|x+4|$, then it would become $u^2-10u=24$. But where did I do wrong? I didn't see it.