The graph of a certain quadratic y = ax^2 + bx + c is a parabola with vertex (4,0) which passes through the point (5,7). What is the value of a?
In every single equation, a is the slope when you take the slope of (x, y_1), which is the vertex, and (x+1, y_2) (underscore means y number 1 or y number 2). Since the vertex (x, y)=(4,0), and the slope between (4,0) and (4+1,7) is 7, a is 7
sorry if it isn't clear I'm not good at explaining things :(