Question

How to solve quadratic equations with the coefficient not equal to 1?

Answer 1

Which coefficient? There are multiple, as the general formula of a quadratic equation is $ax^2+bx+c$.
There are a few ways, and if you can factorise by inspection that works, however the most effective way of solving equations that aren't obvious is to plug it into the quadratic formula:

$\boxed{x=-b +- \frac{ \sqrt{b^2-4ac} }{2a} }$