# Thread: Equation of the normal line?

1. ## Equation of the normal line?

Find the equation of the normal line to the graph of y=√ 8x at x=2.
The part that I'm stuck at is...how do you get the derivative of y=√ 8x? The book gives me 4 / √ 8x for the derivative. How do you get that?

I know how to do the rest, just not how to take the derivative of that type of function

Thanks so much

2. ## Re: Equation of the normal line?

Their notation is very messy, in my opinion.

$y=\sqrt{8x}=2\sqrt{2}\cdot x^{0.5}$

Now apply the power rule. If you prefer, you can go straight into the power rule, as we have $8^{0.5}x^{0.5}$ and the $8^{0.5}$ is just a constant. Either way, I'd avoid their notation if possible; I get an answer of $\sqrt{\frac{2}{x}}$ which is equivalent to theirs, although I've simplified slightly.