SOLUTION: Hi. I'm not sure how to find the answer of this kind of equation:
2cos(3x)+1=0. now, i can get as far as cos(3x)= -.5 and replace the 3x with an "a" and divide. I now get 3x=2pi/3
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-> SOLUTION: Hi. I'm not sure how to find the answer of this kind of equation:
2cos(3x)+1=0. now, i can get as far as cos(3x)= -.5 and replace the 3x with an "a" and divide. I now get 3x=2pi/3
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Question 64455: Hi. I'm not sure how to find the answer of this kind of equation:
2cos(3x)+1=0. now, i can get as far as cos(3x)= -.5 and replace the 3x with an "a" and divide. I now get 3x=2pi/3 and 4pi/3. my problem is that i have to solve over a (0, 2pi] domain, and i'm not sure how to alter the domain once i divide my answers by 3. please help! thanks. Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! 2cos(3x)+1=0
cos(3x)=-1/2
Take the arccos of both sides to get:
3x=120 degrees or (2/3)pi radians
x=40 degrees or (2/9)pi radians
Cheers,
Stan H.
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