- Sat Oct 13, 2012 5:29 am
- Forum: Calculus
- Topic: Increasing/Decreasing intervals for Trig
- Replies:
**6** - Views:
**7842**

Matt, thanks a zillion!

- Sat Oct 13, 2012 2:29 am
- Forum: Calculus
- Topic: Increasing/Decreasing intervals for Trig
- Replies:
**6** - Views:
**7842**

Sorry to bug you again but my function was f(x)=20x-10sin(4x)

After taking the derivative I get f'(x)=20-10*4*cos(4x) = 20-40cos(4x)

So, I did take the derivate of 4x!

After taking the derivative I get f'(x)=20-10*4*cos(4x) = 20-40cos(4x)

So, I did take the derivate of 4x!

- Fri Oct 12, 2012 7:20 pm
- Forum: Calculus
- Topic: Increasing/Decreasing intervals for Trig
- Replies:
**6** - Views:
**7842**

I did differentiate that! The problem is with the intervals!

Could you please solve it?

Thank you!

Could you please solve it?

Thank you!

- Fri Oct 12, 2012 2:57 am
- Forum: Calculus
- Topic: Increasing/Decreasing intervals for Trig
- Replies:
**6** - Views:
**7842**

Q: Let f(x)=20x-10sin(4x) for 0<=x<=pi/2 Find the largest interval(s) over which the function f is increasing or decreasing. I tried to solve this: f'(x)=20-40cos(4x) =20(1-2cos(4x)) on keeping f'(x)=0, i get x=pi/12 I just cannot get correct intervals to work properly with my online math homework s...