1. ## Tangent line problem

Hello, I hope someone can help me with this problem:

Let $f(x) = x^2 +ax+b$ for all x. Find values of $a$ and $b$ such that the line $y= 2x$ is tangent to the graph of f at the point (2,4).

Thanks.

2. Nice one.

First you need to find out what the gradient of the tangent is. You do that by differentiating the function. Then you look at what values for a and b give you the equation of the line you've been given.

Need more?