Calculus - derivatives of xtan(x)

In summary, to find the second derivative of y=x tanx, take the derivative of the first derivative using the product rule and the chain rule. The second derivative is 2 x sec(x)^2 tan(x).
  • #1
jendoley
3
0
Find the first and second derivative--simplify your answer.

y=x tanx

I solved the first derivative.
y'=(x)(sec^2(x)) +(tanx)(1)
y'=xsec^2(x) +tanx

I don't know about the second derivative though.
 
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  • #2


jendoley said:
Find the first and second derivative--simplify your answer.

y=x tanx

I solved the first derivative.
y'=(x)(sec^2(x)) +(tanx)(1)
y'=xsec^2(x) +tanx

I don't know about the second derivative though.
Take the derivative of y' to get y''. You will need the product rule and the chain rule.
 
  • #3


(u v)''=u'' v+2 u' v'+u v''
recall
x''=0
and
tan'(x)=sec(x)^2=1+tan(x)^2
so
tan''(x)=(1+tan(x)^2)'=2 tan(x) tan'(x)
 
  • #4


That's what I don't get how to do... The second derivative. I'm assuming I have the first derivative done right. I'm lost after that.
 
  • #5


To find the second derivative take derivative of te derivative.
your function is of the form
y=u v
where u=x and v=tan(x)
y'=u' v+u v'
y''=u'' v+2u' v'+u v''
now we we know u' and v' we need only find u'' and v'' and substitute them in
u=x
u'=1
u''=0
v=tan(x)
v'=1+tan(x)^2=sec(x)^2
v''=2 tan(x) tan'(x)=2 tan(x)+2 tan(x)^3=2 tan(x) sec(x)^2
 

FAQ: Calculus - derivatives of xtan(x)

What is the derivative of xtan(x)?

The derivative of xtan(x) is sec^2(x) + xtan(x).

How do you find the derivative of xtan(x)?

To find the derivative of xtan(x), you can use the product rule or the quotient rule. Alternatively, you can rewrite xtan(x) as x * tan(x) and use the chain rule.

Why is the derivative of xtan(x) important?

The derivative of xtan(x) is important because it allows us to calculate the rate of change of a function that involves both x and tan(x). It is also used in many applications, such as optimization problems and physics equations.

Can the derivative of xtan(x) be simplified?

Yes, the derivative of xtan(x) can be simplified using trigonometric identities. For example, sec^2(x) + xtan(x) can be rewritten as sec(x) * (tan(x) + x).

How can the derivative of xtan(x) be applied in real life?

The derivative of xtan(x) can be applied in real life in various fields, such as engineering, physics, and economics. For example, it can be used to calculate the velocity of a moving object, the rate of change of a stock price, or the optimal angle for a ramp.

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