Question

Verify the identity.

cos 4x + cos 2x = 2 – 2 sin^2 2x – 2 sin^2 x

Answer 1

cos4x = cos2(2x) = 1 - 2sin^2 2x
cos2x = 1 - 2sin^2 x
just joining the sum of them

Answer 2

Is that the answer?

Answer 3

exactly, yeah... :)

Answer 4

Okay, thank you. Do you mind helping me with another question? :o)

Answer 5

cos4x + cos2x = 1 - 2sin^2 2x + 1 - 2sin^2 x = 2 - 2sin^2 2x - 2sin^2 x
LHS = RHS

Answer 6

i'll try

Answer 7

Confirm that f and g are inverses by showing that f(g(x)) = x and g(f(x)) = x.

\[f(x)=\frac{ x-7 }{ x+3 }\]\[g(x)=\frac{ -3x-7 }{ x-1 }\]

Answer 8

@RadEn Do you know how to do this?