<aside> ✅ The linearization of $f$ at $a$ is the function $L(x) = f(a) + f’(a)(x-a)$

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• This formula is for the tangent line to $f$ at $a$, the linear aproximation is the tangent line written as a function $L(x)$
• Sometimes, the linear approximation is written as follows: $\triangle y \approx f'(a) \triangle (x)$ for all $x$ near $a$
  • $\triangle x = (x-a)$, the displacement of $x$ from $a$
  • $\triangle y = f(x) - f(a)$, the resulting change in y-values