Find all solutions to the equation. cos^2 x +2cosx+1=0

asked May 13, 2022 193k views

3 votes

Find all solutions to the equation.
cos^2 x +2cosx+1=0

8.0k points

Please log in or register to add a comment.

3 votes

$x= \pi$

Explanation:

$\cos^2x+\cos x+1=0$

Let
$u= \cos x$

Then
u^2+2u+1=(u+1)^2=0

$\cos x = -1$

This gives us
$x= \pi$ or all integer multiples of
$\pi (n \pi)$

Randall Hauch answered May 18, 2022