Question

find all the critical points 3r/7r^2+8

Answer 1

did you take the derivative?

Answer 2

you should get
\[\frac{-3(7x^2-8)}{(7x^2+8)^2}\]

Answer 3

then set
\[7x^2-8=0\] and solve in two steps \[7x^2=8\]
\[x-\pm\sqrt{\frac{8}{7}}\]