Let l(n) = 2cosnx, n belong to natural number then l(1) l(n+1) l(n)
Let I (n)=2cos n x, nϵN, then I(1)I(n+1)-I(n)=___
Let I(n) = 2cos nx ∀n∈N, then I (1).I(n+1) - I(n) is equal to