Question

Find solutions in the interval [0, 2pi)
2secx+1=cosx

Answer 1

secx=1/cosx
then
2secx-cosx=-1
(2/cosx)-cosx=-1
(2-cos^2(x))/cosx=-1
2-cos^2(x)=-cosx
cos^2x-cosx-2=0
(cosx-2)(cosx+1)=0
either cosx=2 (not possible, because -1<=cosx<=1)
or cosx=-1, then x= pi

Answer 2

thank you soooo much.

Answer 3

u r welcome