2x²+15x+16 = 0

Using quadratic formula:

Using that it seems to be correct.

(b) (2x-1)(3x+2) - (x+3)(2x+1) = 0

Multiply the brackets ...

Using discriminant b^2 - 4ac .... 36 - 4 x 4 x - 5, it seems to have two roots.

Yes, re-arrange it to the left hand side.Also a quick question, if a quadratic equation does not have a equal zero do i need to do something to the expression before trying to solve the quadratic.