I know that you set them equal first so 3x^2+2=ax-1, but then I do not know what to do plz help.
I am not sure what you are referring to. You did not provide the problem. Are you trying to solve for one variable? To solve for $\displaystyle x$, use the quadratic equation. To solve for $\displaystyle a$, add 1 to both sides, then divide both sides by $\displaystyle x$.