Find the first two terms, in ascending powers of uuu, of the binomial expansion of
(1+2u)13 (1 + 2u)^{\frac{1}{3}} (1+2u)31Hence, for small values of xxx, show that
cos3x+1−x23≈A+Bx+Cx2 \cos 3x + \sqrt[3]{1 - x^2} \approx A + Bx + Cx^2 cos3x+31−x2≈A+Bx+Cx2where AAA, BBB and CCC are constants to be found.