Here's the question you clicked on:

55 members online
• 0 viewing

## sandy524 3 years ago find the derivative of f(x) = cos(x) − sin^2(x) on [0,2pi] Delete Cancel Submit

• This Question is Closed
1. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

i now know that its -sin(x)(2cos(x)+1)

2. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

can yu guys help me find the critical points

3. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

Are you sure it ask you to find f'(x) on [a,b]?

4. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

If so, you did that. You are done.

5. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

yes. may you help me find the critical points of this now

6. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

Set f'(x)=0 and solve for x to find the critical numbers.

7. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

You only need to solve this on the interval [0,2 pi]

8. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

can we do it together please

9. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

You are already factored f'(x) Now set both factors equal to 0.

10. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

how? can we work out the problem

11. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

12. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

Yes. I'm walking you through it. You have -sin(x)*(1+2cos(x))=0 Set both factors equal to 0.

13. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

ok

14. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

Just like if you have a*b=0 then either a=0 or b=0 or both=0

15. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0
16. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

this is all i have

17. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

18. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

Use your unit circle. Keep in mind you only have to look between 0 and 2pi

19. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

You have -sin(x)=0 or 1+2cos(x)=0 Solve both of these for the trig function. Solve the first one for sin(x) and solve the second one for cos(x). Tell me what you get after doing this.

20. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

-sinx=pin

21. sandy524
• 3 years ago
Best Response
You've already chosen the best response.
0

$\pi n$

22. myininaya
• 3 years ago
Best Response
You've already chosen the best response.
0

Well you are trying to solve -sin(x)=0 for x. You could divide both sides by -1 since -1 will never be 0. Try solving this: sin(x)=0 Then we will come back to 1+2cos(x)=0

23. Not the answer you are looking for?
Search for more explanations.

• Attachments:

Find more explanations on OpenStudy

##### spraguer (Moderator) 5→ View Detailed Profile

23

• Teamwork 19 Teammate
• Problem Solving 19 Hero
• You have blocked this person.
• ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9999293088912964, "perplexity": 9259.340374680178}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-48/segments/1448398460982.68/warc/CC-MAIN-20151124205420-00009-ip-10-71-132-137.ec2.internal.warc.gz"}