Question

How do I solve for the derivative of y=r/sqrt(r^2+1)?

Answer 1

y'={1.sqrt(r^2+1)-r (2r)/2sqrt(r^2+1) }/(r^2+1) 
simplify . 

Remember (a/b)'=(a'b-b'a)/b^2 

and remember (sqrt(u))'=u'/2sqrt(u)