Rate of reaction

For a reaction say
$$\ce{nA->B}$$ with $$\text{rate} =k[A]^n$$
So do we write rate as $ \frac {-\mathrm d[A]}{\mathrm dt}$ or $\frac{1}{n} \frac {-\mathrm d[A]}{\mathrm dt}$ We have only been taught for $n = 1$, and I couldn't thin which one should be correct. It will be really helpful if you can also include the reason why.


