Hello Guys

I Need some Help in Fonctions

The function f is set to R:

F (x) = 3x 4x ^ 2 -1/2

1. Calculate f (-1), f (-1/2), f (1 / 2) and f (1){ i did this)

2. Proving that the equation f (x) = 0 admits three distinct solutions, ranging from

-1 And 1

3. Let x = cos (alfa)

Express cos3 (alfa), according to cos (alfa)

2. Determiner solutions of the equation f (x) = 0

my second question for x between 0 and 2pie, solvecos(4x)=sin(2x) {edit : i solved this No need to solve it again lol:D

and my last question :

Prove that the equation sinx -1/2 = 0

In admits } 0, 2 (pi) {a unique solution

Thanks In Advance :)