find tan4x? tanx=1/5

Question

hartnn · Answer

@TheMightyThumb  Hi,

$\huge \color{red}{\text{Welcome to Open Study}}\ddot\smile$

you can use the formula 
$\large \tan2x=\dfrac{2\tan x}{1-\tan^2x}$
to get tan 4x , once to find tan 2x from tan x and once more to find tan 4x from tan 2x

anonymous · Answer

Wait , so whats the answer

hartnn · Answer

you can use the formula to get the answer by yourself! 
first find tan 2x using that formula, what u get ?

hartnn · Answer

Aslo, its against our code of conduct to give out direct answers, you can check it out : http://openstudy.com/code-of-conduct

anonymous · Answer

I got 5/2 for tan2x. What should I do next?

hartnn · Answer

tan 2x = 2/5 / (1-1/25) = 2/5 /(24/25) = 2*25/ (24*5) = 5/12 
did you mean 5/12 and not 5/2 ??

hartnn · Answer

anyways, next will be 
$\large \tan4x=\dfrac{2\tan 2x}{1-\tan^22x}$

anonymous · Answer

Oh mb. Couldnt read my writing lol

hartnn · Answer

using same formula and tan2x = 5/12, find tan 4x :)
can you ?

anonymous · Answer

So just plug in 5/12 for tan2x?

hartnn · Answer

yes, absolutely :)

anonymous · Answer

I got 120/119. Is that right? Thanks

hartnn · Answer

That is absolutely correct! 
good work :) 
welcome ^_^

anonymous · Answer

We need more people like you in the world. Thanks ^-^

hartnn · Answer

you'll find them in OpenStudy itself :) 
many more ;) 
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Have a good day :)

anonymous · Answer

I will definitely come here more often. Thanks :)