Question

Help please: 2cos^2x-cosx=1
what's x?

Answer 1

les y = cos(x) then solve 2y^2-y-1 =0
then plug in for y at the end

Answer 2

let*

Answer 3

\(\bf 2cos^2x-cosx=1\implies 2{\color{red}{ cos}}^2{\color{red}{ (x)}}-{\color{red}{ cos}}{\color{red}{ (x)}}-1=0\) <---- notice tis just a quadratic equation, thus solve it likewise

Answer 4

pretty

Answer 5

ok I will try thanks