Thread: Exponential function disguised as a quadratic

This is what I tried:









Solving the above quadratic doesn't give me the right answers, unless I solved it wrong, but I don't think I did. What did I do wrong?

Fatal mistake, the way you are factoring the exponential pieces. You can not factor the 5 out like that, or the 1 like that.

Originally Posted by Phire

[snip]

Are you sure this is the correct equation? I'll bet it's meant to be but you made an incorrect 'simplification' to this before posting.

If so then you're meant to factorise it as . Now solve for x.

I came to the same conclusion today while at school, this problem has been bugging me for 24 hours. Me and 4 other grad students worked on it over lunch to no avail, no way the problem posted as is should be assigned in a pre calculus class, maybe a numerical methods course at best.

If it is as Mr. Fantastic suggested (and I hope it is) simply substitute and solve the quadratic to see how he got his factoring, then you are basically done.