Linear approximation to 1/0.254 The question says: Use linear approximation to approximate $1/0.254$. I know that $1/0.25 = 4$. Where do I proceed from next. Do I subtract $0.004$ from the answer, or what else could I do?

Let's consider the function $f(x)=\frac{1}{x}$.  We can find the tangent line $L(x)$ of $f$ at $x=\frac{1}{4}$, and then evaluate $L(.254)$ to obtain our linear approximation.
See if you can find $L(x)$ and finish the proof.
