Helppp! tan²x+4tanx+1=0 [0,2pi)

How do you do it? I tried factorising it which isn't possible.

so i used -b+-squareroot of(b^2-4ac)

which got me stuck at (-4 plusminus squareroot of 12 ) / 2

i don't know what to do next.

thanksss

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- Nov 5th 2008, 09:33 PMleo037tan²x+4tanx+1=0 help!!
Helppp! tan²x+4tanx+1=0 [0,2pi)

How do you do it? I tried factorising it which isn't possible.

so i used -b+-squareroot of(b^2-4ac)

which got me stuck at (-4 plusminus squareroot of 12 ) / 2

i don't know what to do next.

thanksss - Nov 5th 2008, 09:56 PMSoroban
Hello, leo037!

Quote:

$\displaystyle \tan^2\!x+4\tan x+1\:=\:0$

I tried factorising it which isn't possible.

So i used the Quadratic Formula

which got me stuck at: .$\displaystyle \frac{-4 \pm\sqrt{12}}{2} \:=\:-2 \pm\sqrt{3}$

i don't know what to do next.

$\displaystyle x \;=\;\tan^{-1}(\text{-}2+\sqrt{3}) \:=\:\text{-}\,\frac{\pi}{12}\;\;(\text{-}15^o)$

$\displaystyle x \;=\;\tan^{-1}(\text{-}2-\sqrt{3}) \;=\;\text{-}\,\frac{5\pi}{12}\;\;(\text{-}75^o)$