Question

Simplify using the double-angle formula: x3 - 2x3 sin2 (x + 1).

A. x3 cos (x + 1)
B. x3 cos (2x + 1)
C. x3 cos 2(x + 1)
D. x3 cos2 (x + 1)

Answer 1

can someone help me

Answer 2

I can't help you with this one, but I'll try to find someone else who can :) alright?

Answer 3

\[x^3 - 2x^3 \sin^2 (x + 1)\]
First factor out \(x^3\)
\[x^3(1-2\sin^2(x+1))\]
let u=x+1
\[x^3(1-2\sin^2(u))\]
Using identity
\[\cos(2u)=1-2\sin^2(u),\]we have
\[x^3\cos(2u)\]
Then
\[x^3\cos(2(x+1))\]