Biết rằng , với là các số thực. Tính .

Giải thích

Ta có: sin 6 x + cos 6 x = sin 2 x + cos 2 x - 3 sin 2 x . cos 2 x sin 2 x + cos 2 x " src="https://img-question-vn.ruangguru.com/ZYjdUDKlQOQERNdjAngCvbQQbe0i1cvXHOon5qfisiAQViWuA0p8lTK_fnL_-y1kECzvKKulfHQhRVou4hwK_aQEQWF6ze60RbiZCpAPgqTtU3z6ovYuCacWsL7eirXHhtlair03" style="width: 302.05px; height: 41.02px; margin-left: 0.00px; margin-top: 0.00px; transform: rotate(0.00rad) translateZ(0px); -webkit-transform: rotate(0.00rad) translateZ(0px);" title="sin to the power of 6 x plus cos to the power of 6 x equals open parentheses sin squared x plus cos squared x close parentheses minus 3 sin squared x. cos squared x open parentheses sin squared x plus cos squared x close parentheses"> . Vậy . Do đó .