How do you find the general solutions for #2cos^(2)x + 3cosx -2 = 0#?

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How do you find the general solutions for #2cos^(2)x + 3cosx -2 = 0#?

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Answer 1 · 2015-10-21T04:53:27

#60# degrees
or
#pi/3# radians

Explanation:

Treat #cosx# as just #x#, so now we get #2x^2+3x-2=0#
Factor: #(2x-1)(x+2)=0#
Now replace #x# with #cosx#:
#(2cosx-1)(cosx+2)=0#
Now find out #x#
1:
#2cosx-1=0#
#2cosx = 1#
#cosx=1/2#
#x=60#

2:
#cosx=-2#
#x=und#

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How do you find the general solutions for #2cos^(2)x + 3cosx -2 = 0#?

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