how do I multiply 2sqrt 5 by 2?

Question

her is the full problem. (1+2sqrt5)(2+ 4sqrt10), so in trying to FOIL I am trying to multiply 2 by 2sqrt5

Answer 1

Hi Helena,

 

(1+2sqrt5)(2+ 4sqrt10) FOIL

= 2 + 4sqrt(10) + 4sqrt(5) + 8sqrt(50)

= 2 + 4sqrt(10) + 4sqrt(5) + 40sqrt(2)