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November 01, 2025, 03:19:26 pm
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Author Topic: Finding exact solutions  (Read 832 times)  Share 

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samsiexD

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Finding exact solutions
« on: April 25, 2013, 03:47:22 pm »
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Hey so i'm stuck on a question i did one step but didnt know where to go next :P

Find the exact solution to:
Sin(4x)=cos(2x) for xE[-pi,pi]
I did
2sin(2x)cos(2x)=cos(2x) but didn't know what to do next


Help is appreciated :)
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brightsky

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Re: Finding exact solutions
« Reply #1 on: April 25, 2013, 03:52:49 pm »
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so subtract cos(2x) from both sides of the equation, factorise the cos(2x) out and then use null factor law to find the solutions.
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Jeggz

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Re: Finding exact solutions
« Reply #2 on: April 25, 2013, 03:53:42 pm »
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So continuing on from yourself -






Now you have two equations that you can solve. The first one being and the second one being

Hope that helps  :)

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samsiexD

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Re: Finding exact solutions
« Reply #3 on: April 25, 2013, 04:01:32 pm »
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Okies, thanks to both :)
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