`6cos^2(x) - 3` Use a double angle formula to rewrite the expression.

By the double angle formula for cosine,

`cos(2x)=2cos^2x-1.`

Therefore our expression is equal to

`6cos^2(x)-3=3(2cos^2(x)-1)=3cos(2x).`

By the double angle formula for cosine,

`cos(2x)=2cos^2x-1.`

Therefore our expression is equal to

`6cos^2(x)-3=3(2cos^2(x)-1)=3cos(2x).`