ta có: N=6-\(\sqrt{11}\)
=\(\sqrt{36}\)-\(\sqrt{11}\)
ta có \(\sqrt{31}\)<\(\sqrt{36}\);\(\sqrt{13}\)>\(\sqrt{11}\)
\(\Rightarrow\)\(\sqrt{31}\)-\(\sqrt{13}\)<\(\sqrt{36}\)-\(\sqrt{11}\)
\(\Leftrightarrow\)\(\sqrt{31}\)-\(\sqrt{13}\)<6-\(\sqrt{11}\)
pn giải dùm mk mấy bài kia nữa ik mk cần gấp lắm