Question

cirtical points : photo attached

Answer 1

i got f(x)"=9+(-9)x^2

Answer 2

\[f(x)=9-9(x)^{-2}\]

Answer 3

your first derivative should be \(\large f'(x)= 9-9x^{-2}=9-\frac{9}{x^2}\)

to find the critical numbers, set this equal to zero and solve for x...
ie, solve the equation for x: \(\large 0=9-\frac{9}{x^2} \)

Answer 4

yea its not critical points.
it asking local max and min