hieu31320001

$sinx\sqrt{1+2sinx}=cos2x$

$(x+2)(\sqrt{x+1}+6)+11\leq (4x+5)\sqrt{2x+3}$

Tính $S= \sum_{k=1}^{n} \frac{(-1)^{k}kC_{n}^{k}}{(k+1)(k+2)}$

$x+2\sqrt{\frac{3x-1}{5}}=4\sqrt[4]{\frac{x^{4}+4}{20}}$

Cho $(a_{n}):\left\{\begin{matrix} & a_{1}=\frac{4}{3}\\ & (n+2)^{2}a_{n}=n^{2}a_{n+1}-(n+1)a_{n}a_{n+1} \end{matrix}\right.$

Tìm Lim an