Finding the Gradient of a Quadratic Function

Use the blue sliders to change the coefficients of the quadratic. Use the orange slider to move the point.
Note the value of x and the gradient of the tangent, which you can take from its equation. Try a few different points and see how the gradient varies with x. Try to establich a rule that connects the x-value and the gradient. Now try a different quadratic function and repeat. What is the rule for working out the gradient for a general quadratic function