$$y=-x^2+2x+9$$ $$y=-5x^2+10x+12$$ Round answer to two decimal places.
So far I made both equations equal the other which lead to $-4x^2+8x+12$, took $4$ out, $4 (-x^2+2x+3)$. Then that bracketed terms were put into the quadratic formula to equal $(-1 \pm \sqrt{2})/(-1)$
That answer doesn't seem right, but I'm not sure where I went wrong.
Quadratic formula :
$$x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$$
we have $$y=-x^2+2x+9$$ and $$y=-5x^2+10x+12$$ eliminating $y$ we have $$-5x^2+10x+12=-x^2+2x+9$$ and from here we get a quadratic equation $$0=4x^2-8x-3$$ using the quadratic fomula we obtain: $$x_1=\frac{2+\sqrt{7}}{2}$$ or $$x_2=\frac{2-\sqrt{7}}{2}$$