a)[tex] 2^{n-1}= 2^{14};n-1=14;n=15 \\ b) T_{2+1}= C^2_{15} ( \sqrt{x}) ^{13}(- \frac{1}{ \sqrt[3]{x} })^2= -\frac{15!}{2!13!} x^{ \frac{13}{2}-\frac{2}{3} }= - \frac{14*15}{2} x^{ \frac{35}{6} }= \\ =-105 \sqrt[6]{ x^{35} }=-105x^5 \sqrt[6]{x^5} \\ [/tex]
