Question 731576
{{{4sqrt(5)+sqrt(5)}}} are radicals. When you add radicals together when they have the same square root, all you have to do is add the numbers in front of the square root. When there is no number in front of a radical, there always has a one in front. So, {{{4sqrt(5)+sqrt(5)}}} becomes (1+4){{{sqrt(5)}}}, then {{{5sqrt(5)}}}. So simplified, your answer is {{{5sqrt(5)}}}.
For more on adding/subtracting radicals, see: http://www.purplemath.com/modules/radicals3.htm