Question

How to simplify
the square root of 45 plus 4 square root 5

Answer 1

*reposted*

first note that we can't combine radicals if the radicands (term inside a radical sign) are not equal.
notice that we can further simplify squareroot of 45 as
sqrt(45) = sqrt(3*3*5) = sqrt(3^2 * 5) = 3*sqrt(5)
now, we can combine them:
3*sqrt(5) + 4*sqrt(5)
7*sqrt(5)

hope this helps~ :)