A curve with equation y = ax^2 + bx + c crossed the x-axis at (-4,0) and (0,0) and also passes through the point (2,120). Where does the curve cross the y-axis?
You have been given three points, being three sets of values for $\displaystyle x$ and $\displaystyle y$. Plug these values into the given equation:
. . . . .$\displaystyle 0\, =\, 16a\, -\, 4b\, +\, c$
. . . . .$\displaystyle 9\, =\, c$
. . . . .$\displaystyle 120\, =\, 4a\, +\, 2b\, +\, c$
Solve the system of equations.