Andrew K. answered 11/23/19
Student-Athlete and Physics/Computer Science Double Major at MIT
The slope of the function y=2x^2 is given by the derivative dy/dx = 4x. If we evaluate dy/dx at the point (1,2) we get dy/dx = 4 because x = 1 at (1,2). We now know the slope of this line and a point it goes through so we can put it into point slope form, so y-2 = 4(x-1). Putting this into slope-intercept form we get y=4x-2.
Hope this helps! Let me know if you need me to clarify anything.