Question

my classmate question Find the value of x so that dy/dx = 0 if y = tan^-1 (x/9) - tan^-1 (x/16).
a. ± 10
b. ± 9
c. ± 11
d. ± 12

Answer 1

my answer is ± 12 but i wanted to be sure

Answer 2

so the derivative of that monster is even uglier: -(7 (-144+x^2))/((81+x^2) (256+x^2)), and you would be correct in asserting that x=±12

Answer 3

hahaha