# Integration by parts help please

#1

I need help on q3e. I don't understand how

dv/dx = 2secxsecxtanx

means that

v=sec^2x

Thanks
0
8 years ago
#2
(Original post by krisshP)
[A
I don't understand how

dv/dx = 2secxsecxtanx

means that

v=sec^2x

Thanks
Use a substitution of u=sec x when integrating "2secxsecxtanx" wrt x.

Alternativley, differentiate sec^2x and see what you get.

It doesn't require integration by parts.
0
#3
(Original post by ghostwalker)
Use a substitution of u=sec x when integrating "2secxsecxtanx" wrt x.

Alternativley, differentiate sec^2x and see what you get.

It doesn't require integration by parts.
Sorry, but so far I haven't done integration by substitution, but I have done integration by parts. Maybe I should just reattempt the question after doing integration by substitution? Annoying thing is this question was actually in the chapter of integration by parts .

Thanks anyway.
0
8 years ago
#4
(Original post by krisshP)
Sorry, but so far I haven't done integration by substitution, but I have done integration by parts. Maybe I should just reattempt the question after doing integration by substitution? Annoying thing is this question was actually in the chapter of integration by parts .

Thanks anyway.
OK. You can do it by IBP.

Split as sec d(sec)/dx
0
#5
(Original post by ghostwalker)
OK. You can do it by IBP.

Split as sec d(sec)/dx
Thanks for that. I'll give it a shot later and see what happens
0
8 years ago
#6
(Original post by krisshP)
Thanks for that. I'll give it a shot later and see what happens
You should get something like

Spoiler:
Show

Where "I" is your original integral.

and re-arrange.
0
8 years ago
#7
(Original post by krisshP)
OP

I need help on q3e. I don't understand how

dv/dx = 2secxsecxtanx

means that

v=sec^2x

Thanks
By noticing that

is of the form

,

you should be able to deduce the value of
0
8 years ago
#8
(Original post by krisshP)

I need help on q3e. I don't understand how

dv/dx = 2secxsecxtanx

means that

v=sec^2x

Thanks
If i were you I would intergrate the components seperatly (not sure if this is right though)
0
#9
(Original post by Khallil)

By noticing that

is of the form

,

you should be able to deduce the value of
It worked.

Thanks
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