tìm gtnn của x^5+1/x^2+6 gấp lắm nhanh lên nhé mn!!!!!!!!!!!!!!!!!

Ta có: 6−x2−−−−−√≤6–√6−x2≤6

⇒−26−x2−−−−−√≥−26–√⇒−26−x2≥−26

⇒5−26−x2−−−−−√≥5−26–√⇒5−26−x2≥5−26

⇒A=15−26−x2−−−−−√≤15−26–√=5+26–√⇒A=15−26−x2≤15−26=5+26

⇒MaxA=5+26–√⇔x=0