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# P3 Integration -again! watch

1. Quick integration question, how do i integrate 2tanx + 1 ? (Well, the 2 tanx bit)

Thanks!

Emma x x x
2. (Original post by Emz)
Quick integration question, how do i integrate 2tanx + 1 ? (Well, the 2 tanx bit)

Thanks!

Emma x x x
Use the rule that tanx = (sinx)/(cosx)

then use integration by substituion, where u = cos x

Hope this helps
3. (Original post by Emz)
Quick integration question, how do i integrate 2tanx + 1 ? (Well, the 2 tanx bit)

Thanks!

Emma x x x

∫2tanx+1 dx = ∫2(sinx/cosx)+1 =

2∫(sinx/cox) +1/2 dx

should know that lnf(x)=f'(x)/f(x) therefore

-2lncosx+x/4+c
4. cant you just say the integral of 2tanx + 1 is lnsecx + x + c?
5. (Original post by jazzyj)
cant you just say the integral of 2tanx + 1 is lnsecx + x + c?
You could but I would prefer that you left the 2 in you answer as opposed to making it disappear.
6. (Original post by jazzyj)
cant you just say the integral of 2tanx + 1 is lnsecx + x + c?
Actually, its 2ln|secx| + x + C, which is the same as what the ppl above have written, but without any workings.
7. oops my mistake..i meant 2lnsecx + x

is this correct?
8. (Original post by jazzyj)
oops my mistake..i meant 2lnsecx + x

is this correct?
Yep, and its a **** load easier than the long way that had been previously suggested. I think that the integral is even of the formula sheet if anyone is feeling very lazy or dizzy in the exam.

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