Question

Help with this question

Answer 1

With some simplification,

cos⁻¹(x) - 5 cos⁻¹(x) - π/3 = 2π/3

becomes

-4 cos⁻¹(x) = π

or

cos⁻¹(x) = -π/4

However, the inverse cosine function has a range of 0 ≤ cos⁻¹(x) ≤ π, so there are no solutions to this equation.