If you tried any other combination other than 54x and u would get a negative inside the square root, making things alot more complicated. You can also see that the x's in 54x and will cancel each other out, if you use the AM/GM inequality.
If you tried any other combination other than 54x and u would get a negative inside the square root, making things alot more complicated. You can also see that the x's in 54x and will cancel each other out, if you use the AM/GM inequality.