Find all solutions of the equation in the interval [0, 2π).

Answer:
x=0
Step-by-step explanation:
[tex]4 \cos(x) = - \sin {}^{2} (x) + 1[/tex]
[tex]4 \cos(x) = 1 - \sin {}^{2} (x) [/tex]
[tex]4 \cos(x) = \cos {}^{2} (x) [/tex]
[tex]4 \cos(x) - \cos {}^{2} (x) = 0[/tex]
[tex] \cos(x) (4 - \cos(x) ) = 0[/tex]
[tex] \cos(x) = 0[/tex]
[tex]x = 0[/tex]
[tex]4 - \cos(x) = 0[/tex]
[tex] \cos(x) = 4[/tex]
There is no solution here because cosine is undefined it the range is not between -1 and 1 so the only answer is 0.