Question

If the equation 2cos square theta+cos theta-6=0

Answer 1

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2cos^2x+cosx-6=0

=2cos²x+4cosx-3cosx-6=0

=2cosx(cosx+2)-3(cosx+2)=0

=(cosx+2)(2cosx-3)=0

either cosx=-2 or cosx=3/2=1.5

which is not possible as value of cosx ranges from -1 to 1

hence the given equation is not possible