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November 9th, 2016, 04:35 AM   #1
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Function! Explain please!

Our teacher showed us the answer to f(tanx), if f(b) = b - b^2/1 + b but I don't quite get it..

Someone explain to me how do you get answer for f(tanx), if f(b) = b - b^2/1 + b ??

Last edited by SlayedByMath; November 9th, 2016 at 04:57 AM.
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November 9th, 2016, 04:50 AM   #2
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Your notation doesn't make sense. $f(3)$ must be equal to something.
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November 9th, 2016, 04:56 AM   #3
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Oh no sorry!! I've typed totally wrong!! ><

It's f(b) = b - b^2/ 1 + b

then find just only f(tanx)
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November 9th, 2016, 05:02 AM   #4
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For $f(\tan x)$ you replace $b$ with $\tan x$ wherever it appears.
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November 9th, 2016, 05:19 AM   #5
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then..?

I just saw some tan, sin, cos on the board but I don't actually know how they actually got it? Explain briefly TT.TT
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November 9th, 2016, 06:01 AM   #6
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If f(b) = (b - b^2)/(1 + b) was intended,
f(tan(x)) = tan(x)(1 - tan(x))/(1 + tan(x)) = tan(x)tan(pi/4 - x).
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