SOLUTION: https://gyazo.com/adf6b2eb47c84dfcb40621be331f0cb2 with steps please

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Question 1180927: https://gyazo.com/adf6b2eb47c84dfcb40621be331f0cb2
with steps please
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

2cos%5E2%284x%29-1
use identity
2cos%5E2%28alpha%29+-1=cos%282alpha%29
in your case alpha=4x
=cos%282%2A4x%29
=cos%288x%29