Math Help - derivatives

1. derivatives

let f be a differentiable function such that f(3)=2 and f(3)=5. If the tangent line to the graph of f at x=3 is used to find an approximation to a zero of f, that approximation is??

I have no idea what to do?

2. Originally Posted by gebbal
let f be a differentiable function such that f(3)=2 and f(3)=5. If the tangent line to the graph of f at x=3 is used to find an approximation to a zero of f, that approximation is??

I have no idea what to do?
The equation of the tangent is

$y - f(3) = f'(3) (x-3)$

Find when this line crosses the x-axis.