How do you find a tangent?

If you have a function f(x), then the tangent can be found by deriving f, denoted

d/dx(f(x)) = f'(x). This will give the slope of f(x) at a certain point (a,b).

find f'(a), call this m. Now, use the standard form for a line, y = mx+c, plug in the point (a,b) to solve for c. Finally, the equation for the line tangent to a point (a,b) and f(x) is y= f'(a)x + c