I took it to
The choices are
d)none of these.
Is it none of these?
Can anyone help me? Or at least a hint?
You don't need to use the quadratic formula or even write it as a quadratic equation (if that was your question).
We can write and
Of course, that isn't one of the forms given but you can write in terms of a logarithm, basically by solving a quadratic equation as you have been told!