Let's perform the differentiation: $\frac{\mathrm{d}}{\mathrm{d}x}\left(2x\right)$

ⓘ A constant factor stays in front of the derivative, (k*u)' = k*u': $\frac{\mathrm{d}}{\mathrm{d}x}\left(2x\right)$ = $2$

▶Derivative:   $2$