How does the square root of 20 equal plus or minus 2 the square root of 5?

Question

How was that answer gotten?

 

√20 = + - 2√5

Answer 1

When we have a positive number under the square-root, we can have a positive or negative number.  This is because a positive times a positive is positive.  Also, a negative times a negative is positive.  In addition, when we simplify radicals, we break them down by its factors.

 

 

±√(20) =

 

±√(4)√(5) =

 

±2√(5) =

 

±2√(5)