Question

If tan2x = 4 - 2tanx, then tanx = _____.

a.)-1 ± sqrt 5
b.)-1 ± sqrt 3
c.)1 ± sqrt 3
d.)1 ± sqrt 5

Answer 1

Is it \(tan^2x\)? Then that would make sense.

Answer 2

no wonder why I couldn't find the solution. Yes it is squared.

Answer 3

\[\rm \tan^2x=4-2~tanx\] tanx=sinx/cosx and tan^2x=sec^2x-1
we get
\[\rm \sec^2x-1=4-2 \frac{sinx}{cosx}\]
secx=1/cosx
\[\rm \frac{ 1 }{ cox^2(x) }-1=4-2\frac{sinx}{cosx}\]
\[\frac{ 1-\cos^2x }{ \cos^2x }=4-\frac{ 2sinx }{ cosx }\]
1-cos^2x=sin^2x

Answer 4

stupid me don't know why doing all that work..

Answer 5

\[\rm \tan^2x=4-2tanx\]
\[\rm \tan^2x+2tanx-4=0\]
let tanx= y
\[\rm y^2+2y-4=0\]
solve for y