## Calculus (3rd Edition)

$4x-3$
Linearization of $f(x)$ at $x=a$ is $L(x)=f(a)+f'(a)(x-a)$ Knowing that $f(x)=x^{4}$, $f'(x)=4x^{3}$ and $a=1$, we have $L(x)=1^{4}+4(1)^{3}(x-1)=1+4x-4=4x-3$