Question

Доказать торжество:
4cos ^4x-2cos 2x-1/2 cos4x=3/2

Answer 1

4(1+сos2x)²/4 -2cos2x-1/2*(2cos²2x-1)=3/2
1+2cos2x+cos²2x-2cos2x-cos²x+1/2=3/2
1+1/2=3/2
3/2=3/2