MathematicsMedium64×since 2002Q3014The sum of the coefficient of x2/3x^{2 / 3}x2/3 and x−2/5x^{-2 / 5}x−2/5 in the binomial expansion of (x2/3+12x−2/5)9\left(x^{2 / 3}+\frac{1}{2} x^{-2 / 5}\right)^9(x2/3+21x−2/5)9 isA19/4B69/16C63/16D21/4Check answerSkip