When (1,2) is substituted into the first equation, the equation is true. The ordered pair (1,2) is a solution to the system of linear equations. When (1,2) is substituted into the second equation, the equation is true.
So I'm guessing that the x2 is your way of saying 2 is the exponent right? In that case the equation would be 8x^2 + 12x Well you would have to pull out the gcf which in this case will be 4x after pulling out the gcf you should get 4x(2x + 3)