CMR: \(\frac{12}{\sqrt{13}}\)+\(\frac{13}{\sqrt{12}}\) > \(\sqrt{12}\)+\(\sqrt{13}\)
Những câu hỏi liên quan
Chứng minh bất đẳng thức
\(\frac{12}{\sqrt{13}}+\frac{13}{\sqrt{12}}>\sqrt{12}+\sqrt{13}\)
Ta có:
\(\frac{12}{\sqrt{13}}+\frac{13}{\sqrt{12}}=\frac{12\sqrt{13}}{13}+\frac{13\sqrt{12}}{12}=\frac{13\sqrt{13}-\sqrt{13}}{13}+\frac{12\sqrt{12}+\sqrt{12}}{12}\)\(=\sqrt{12}+\sqrt{13}+\frac{1}{\sqrt{12}}-\frac{1}{\sqrt{13}}>\sqrt{12}+\sqrt{13}\)
Đúng 0
Bình luận (0)
\(\frac{1}{\sqrt{16}-\sqrt{15}}-\frac{1}{\sqrt{15}-\sqrt{14}}+\frac{1}{\sqrt{14}-\sqrt{13}}-\frac{1}{\sqrt{13}-\sqrt{12}}+\frac{1}{\sqrt{12}-\sqrt{11}}-\frac{1}{\sqrt{11}-\sqrt{10}}+\frac{1}{\sqrt{10}-\sqrt{9}}\)
Với n > 0 Ta có:
\(\frac{1}{\sqrt{n+1}-\sqrt{n}}=\frac{\sqrt{n+1}+\sqrt{n}}{\left(\sqrt{n+1}-\sqrt{n}\right)\left(\sqrt{n+1}+\sqrt{n}\right)}=\frac{\sqrt{n+1}+\sqrt{n}}{n+1-n}\)
\(=\sqrt{n+1}+\sqrt{n}\)
\(\Rightarrow\frac{1}{\sqrt{16}-\sqrt{15}}-\frac{1}{\sqrt{15}-\sqrt{14}}+...+\frac{1}{\sqrt{10}-\sqrt{9}}\)
\(=\sqrt{16}+\sqrt{15}-\sqrt{15}-\sqrt{14}+...+\sqrt{10}+\sqrt{9}\)
\(\sqrt{16}+\sqrt{9}=3+4=7\)
Đúng 0
Bình luận (0)
Tính: \(21\sqrt{\frac{3}{7}}-\frac{13}{2\sqrt{3}-5}-\sqrt{21-12\sqrt{3}}\)
\(\sqrt{\frac{13}{24}}\) x \(\sqrt{\frac{12}{13}}\)= ?
Ai nhanh mình tích
\(\frac{13}{24}\times\frac{12}{13}\)
\(=\frac{12}{24}=\frac{1}{2}\)
Học tốt #
Đúng 0
Bình luận (0)
Tính: \(N=\frac{\sqrt{15-10\sqrt{2}}+\sqrt{13+4\sqrt{10}}-\sqrt{11+2\sqrt{10}}}{2\sqrt{3+2\sqrt{2}}+\sqrt{9-4\sqrt{2}}+\sqrt{12+8\sqrt{2}}}\)
giải hệ: \(\hept{\begin{cases}\left(1-\frac{12}{y+3x}\right)\sqrt{x}=2\\\left(1+\frac{12}{y+13}\right)\sqrt{y}=6\end{cases}}\)
Tính \(E=\frac{\sqrt{15-10\sqrt{2}}+\sqrt{13+4\sqrt{10}}-\sqrt{11+2\sqrt{10}}}{2\sqrt{3+2\sqrt{2}}+\sqrt{9-4\sqrt{2}}+\sqrt{12+8\sqrt{2}}}\)
\(12\frac{3}{11}-\frac{6}{13}+3,25-5\frac{3}{11}-4\frac{7}{13}+\sqrt{1\frac{9}{16}}\)
\(=\left(\frac{135}{11}-\frac{58}{11}\right)+\left(\frac{13}{4}+\frac{5}{4}\right)-\frac{6}{13}\)
\(=7+\frac{9}{2}-\frac{6}{13}\)
\(=\frac{23}{2}-\frac{6}{13}\)
\(=\frac{287}{26}.\)
Chúc bạn học tốt!
\(12\frac{3}{11}-\frac{6}{13}+3,25-5\frac{3}{11}-4\frac{7}{13}+\sqrt{1\frac{9}{16}}\)
\(12\frac{3}{11}-\frac{6}{13}+3,25-5\frac{3}{11}-4\frac{7}{13}+\sqrt{1\frac{9}{16}}\)
\(=12+\frac{3}{11}-\frac{6}{13}+3,25-5-\frac{3}{11}-4-\frac{7}{13}+\sqrt{\frac{25}{16}}\)
\(=\left(12-5-4\right)+\left(\frac{3}{11}-\frac{3}{11}\right)+\left(\frac{-6}{13}-\frac{7}{13}\right)+\frac{5}{4}+3,25\)
\(=3+0+\left(-1\right)+1,25+3,25=2+4,5=6,5\)