Question #8842f

1 Answer
Sep 23, 2017

All you need to do is plug #5# into the derivative.

#f'(x)=-sinx-4sec^2x#

#f'(5)=-sin(5)-4sec^2(5)#

You can plug this straight into something like Wolfram Alpha.

On a calculator, depending on what type you have, you may not have the #sec# button and instead have to use #cos#:

#f'(5)=-sin(5)-4/(cos(5))^2#

I also assume you're working with radians. Without knowing how many digits you need, you should get:

#f'(5)=-48.75260255517...#