\(A=\sin^{10}x+\cos^{10}x\) có biểu thức hạ bậc bằng
\(\dfrac{61}{128}+\dfrac{13}{32}\cos4x+\dfrac{3}{128}\cos8x\).\(\dfrac{63}{128}+\dfrac{15}{32}\cos4x+\dfrac{5}{128}\cos8x\).\(\dfrac{65}{128}+\dfrac{17}{32}\cos4x+\dfrac{7}{128}\cos8x\).\(\dfrac{67}{128}+\dfrac{19}{32}\cos4x+\dfrac{9}{128}\cos8x\).Hướng dẫn giải: