To multiply powers of the same base, add their exponents. Add $2$ and $1$ to get $3$.
$$\frac{\mathrm{d}}{\mathrm{d}x}(3x^{3}-2)$$
The derivative of a polynomial is the sum of the derivatives of its terms. The derivative of a constant term is $0$. The derivative of $ax^{n}$ is $nax^{n-1}$.
