Trying to find dy/dx of a trig function # 2

  • Thread starter jtt
  • Start date
  • #1
jtt
16
0

Homework Statement


find dy/dx


Homework Equations


x+tanxy=0


The Attempt at a Solution


d/dy(x+tanxy)

x+sec^2(xy)((1)(dy/dx))+(1)(tanxy)=0
dy/dx(sec^2(xy)+x+tanxy=0
-x-tanxy -x-tanxy
dy/dx(sec^2(xy)/(sec^2(xy)=(-x-tanxy)/(sec^2(xy))

dy/dx=(-x-tanxy)/(sec^2xy)
 

Answers and Replies

  • #2
LCKurtz
Science Advisor
Homework Helper
Insights Author
Gold Member
9,557
767

Homework Statement


find dy/dx


Homework Equations


x+tanxy=0

You can begin by stating the problem unambiguously. Are you trying to differentiate

x + tan(xy) = 0 or x + ytan(x)=0. The point is that as it is written we can't tell whether the y is inside or outside that tangent function. Parentheses are necessary!

The Attempt at a Solution


d/dy(x+tanxy)

Why are you writing d/dy when you are differentiating with respect to x?
 
  • #3
jtt
16
0
trying to differentiate x+tan(xy)

i got dy/dx when i took the derivative of y in tan(xy)
 
  • #4
LCKurtz
Science Advisor
Homework Helper
Insights Author
Gold Member
9,557
767

Homework Statement


find dy/dx


Homework Equations


x+tanxy=0


The Attempt at a Solution


d/dy(x+tanxy)

You mean d/dx(x + tan(xy))

x+sec^2(xy)((1)(dy/dx))+(1)(tanxy)=0
Is the derivative of x equal to x??

And what I highlighted in red should be the derivative of the (xy) which is the argument of the tangent function, or the "inside". There should be no tan(xy) in that.
 

Related Threads on Trying to find dy/dx of a trig function # 2

Replies
1
Views
1K
Replies
4
Views
2K
  • Last Post
Replies
4
Views
4K
  • Last Post
Replies
3
Views
2K
Replies
2
Views
6K
  • Last Post
Replies
3
Views
2K
Replies
9
Views
3K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
4
Views
2K
Top