Answer
$j'(x)=3-x^{-2}$
Work Step by Step
First you have to re-write this number before you can take its derivative. You re-write it as $\frac{3x^2}{x}+\frac{1}{x}$ Then re-write it again $3x+x^{-1}$ Then you take the derivative of that number by applying the derivative rule. A number with an x variable, you take the exponent, multiply it with the number in front, then subtract one from the exponent.