Tolong dijawab dengan caranya,,
Diketahui persamaan cos 2x + cos x = 0, untuk 0 ≤ x ≤
nilai x yang memenuhi adalah.....
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Diketahui persamaan cos 2x + cos x = 0, untuk 0 ≤ x ≤
A.
B.
C.
D.
E.
Takamori37
![\\$Identitas:$ \\ \boxed{\cos 2x=2\cos^2x-1} \\ \\ \cos 2x+\cos x=0 \\ 2\cos^2x-1+\cos x=0 \\ 2\cos^2x+\cos x-1=0 \\ (\cos x+1)(2\cos x-1)=0 \\\\ $Solusi 1:$ \\ \cos x=-1 \\ x=\pi \\\\ $Solusi 2:$ \\ \cos x=\frac{1}{2} \\ x=\frac{\pi}{3} \\\\ $Maka:$ \\ \boxed{\frac{\pi}{3}\text{ dan }\pi\;\;\;[D]}](https://tex.z-dn.net/?f=%5C%5C%24Identitas%3A%24+%5C%5C+%5Cboxed%7B%5Ccos+2x%3D2%5Ccos%5E2x-1%7D+%5C%5C+%5C%5C+%5Ccos+2x%2B%5Ccos+x%3D0+%5C%5C+2%5Ccos%5E2x-1%2B%5Ccos+x%3D0+%5C%5C+2%5Ccos%5E2x%2B%5Ccos+x-1%3D0+%5C%5C+%28%5Ccos+x%2B1%29%282%5Ccos+x-1%29%3D0+%5C%5C%5C%5C+%24Solusi+1%3A%24+%5C%5C+%5Ccos+x%3D-1+%5C%5C+x%3D%5Cpi+%5C%5C%5C%5C+%24Solusi+2%3A%24+%5C%5C+%5Ccos+x%3D%5Cfrac%7B1%7D%7B2%7D+%5C%5C+x%3D%5Cfrac%7B%5Cpi%7D%7B3%7D+%5C%5C%5C%5C+%24Maka%3A%24+%5C%5C+%5Cboxed%7B%5Cfrac%7B%5Cpi%7D%7B3%7D%5Ctext%7B+dan+%7D%5Cpi%5C%3B%5C%3B%5C%3B%5BD%5D%7D "\\$Identitas:$ \\ \boxed{\cos 2x=2\cos^2x-1} \\ \\ \cos 2x+\cos x=0 \\ 2\cos^2x-1+\cos x=0 \\ 2\cos^2x+\cos x-1=0 \\ (\cos x+1)(2\cos x-1)=0 \\\\ $Solusi 1:$ \\ \cos x=-1 \\ x=\pi \\\\ $Solusi 2:$ \\ \cos x=\frac{1}{2} \\ x=\frac{\pi}{3} \\\\ $Maka:$ \\ \boxed{\frac{\pi}{3}\text{ dan }\pi\;\;\;[D]}")
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