How do you solve $cosx=3cosx+1$ ?

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Answer 1 · 2016-07-26T16:32:05

$x=2kpi+-2pi/3, k in ZZ$ .

$cosx=3cosx+1$

$rArr -2cosx=1$

$rArr cosx=-1/2=-cos(pi/3)=cos(pi-pi/3)=cos2pi/3...(1)$

Now, we can use the soln. to the eqn. $costheta=cosalpha$ is,

$theta=2kpi+-alpha, k in ZZ$

Using this soln. for $(1)$ , we get,

$x=2kpi+-2pi/3, k in ZZ$ .

How do you solve cosx=3cosx+1cosx=3cosx+1?