How do you simplify #2sqrt20 + 8sqrt45 - sqrt80#?

1 Answer
Jun 9, 2016

Answer:

You first factorise everthing under the root, trying to find squares:

Explanation:

#20=4xx5=2^2xx5#
#45=9xx5=3^2xx5#
#80=16xx5=4^2xx5#

We can take the squares out from underneath the roots
#sqrt20=2sqrt5#
#sqrt45=3sqrt5#
#sqrt80=4sqrt5#

We may add roots with the same argument:

#2sqrt5+3sqrt5+4sqrt5=(2+3+4)sqrt5=9sqrt5#