Weird Derivative problem

  • #1

Homework Statement





30958vq.jpg






Homework Equations


Trig identities or straightforward derivative?


The Attempt at a Solution


Is the answers

1. C
2. B
3. A
4. D

I tried taking the derivative of these, but a friend of mine here told me it deals with trig identities and isn't a derivative equation at all. Is he wrong ?

I am pretty sure these are the solutions but i want to double check ...
 

Answers and Replies

  • #2
35,294
7,152
Your friend is wrong. You hae to take the derivatives of the four given functions, and then match the derivatives you got with the answers shown by using trig identities. For 1, C is correct. For the rest, use trig identities to simplify the answers and compare your results with the derivatives you got for the given functions.
 
  • #3
2. y= tan(x)
y'= sec^2(x)
Answer: D
trig identity used: 1+tan^2(x)= sec^2(x)

3. y=cos(tan(x))
y'= -sec^2(x)*sin(tan(x))
Answer: A

4.y=sin(x)tan(x)
y'=cos(x)*tan(x)+sec^2(x)*sin(x)
Answer: B

Is this correct? Thank you for the quick response by the way.
 
  • #5
Thank you ! problem solved
 

Related Threads on Weird Derivative problem

  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
10
Views
1K
  • Last Post
Replies
4
Views
1K
Replies
3
Views
862
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
2
Views
857
  • Last Post
Replies
2
Views
855
  • Last Post
Replies
6
Views
2K
Top