Đáp án+Giải thích các bước giải:
`\frac{1}{(n+1)\sqrt{n})`
`=\frac{\sqrt{n}}{n(n+1)}`
`=\sqrt{n}(\frac{1}{n(n+1)})`
`=\sqrt{n}(\frac{n+1-n}{n(n+1)})`
`=\sqrt{n}(\frac{n+1}{n(n+1)}-\frac{n}{n(n+1)})`
`=\sqrt{n}(1/n-1/(n+1))`
`=\sqrt{n}(1/(\sqrt{n})-1/(\sqrt{n+1}))(1/(\sqrt{n})+\frac{1}{\sqrt{n+1}})`
`=(1-\frac{1}{\sqrt{n+1}})(\frac{1}{\sqrt{n}}+\frac{1}{\sqrt{n+1}})`