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**1. Homework Statement**

Find the derivative of the following function. Simplify where possible.

y=31*arctan(sqrt(x))

**2. Homework Equations**

I know that the derivative of arctan(x) = 1 / (1+x

^{2})

I also know we will be using chain rule and product rule.

**3. The Attempt at a Solution**

y' = (31)'[arctan(sqrt(x))] + (31)[arctan(sqrt(x))]'

y' = (0)[arctan(sqrt(x))] + (31)*[1/(1+x

^{2})] * (2sqrt(x))

y' = 31 / (2sqrt(x))(1+x

^{2})

However the correct answer is

y' = 31 / (2sqrt(x))(1+x) <-- no x

^{2}

I'm not sure why the x

^{2}ends up being just x. I checked if it was simplifying problem but that wasn't it (at least not from what I see).

Thanks for the help in advance.