How do you solve #2cos^2x-5cosx+3=0#?

1 Answer
Nghi N
Apr 9, 2018

#x = 2kpi#

Explanation:

Solve this quadratic equation for cos x:
#f(x) = 2cos^2 x - 5cos x + 3 = 0#.
Since a + b + c = 0, use shortcut.
cos x = 1, and cos #x = c/a = 3/2# (rejected as > 1)
cos x = 1 --> x = 0, and #x = 2pi#
General answer:
#x = 2kpi#

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