Here is the function $\displaystyle y=x*sqrt[a+b*x^2]$

the tangent equation of the function at $\displaystyle x=sqrt[5]$

is $\displaystyle x+2y=5*sqrt[5]$

A. Find a and b.

B. Find the function definition range.

C. Find the minimum & maximum points.

We tried to derive the function but we didn't succeed.

Please help us to finish the question.

Thanks.