Question

What is the simplest form of the expression?

Answer 1

The answer is C. 4√5 

To calculate this, we must find the greatest common divisor of these 3 numbers √20,√45, and √5.
The greatest common divisor is √5:
$\sqrt{20} = \sqrt{5*4} = \sqrt{5} * \sqrt{4} = \sqrt{5} *2= 2\sqrt{5}$
$\sqrt{45} = \sqrt{5*9} = \sqrt{5} * \sqrt{9}=\sqrt{5}*3 = 3\sqrt{5}$

Therefore,
$\sqrt{20} + \sqrt{45}- \sqrt{5}=2 \sqrt{5} +3\sqrt{5}-1\sqrt{5}=\sqrt{5}(2+3-1)=4\sqrt{5}$

Answer 2

Simplify 20−−√20 to 25√25
25√+45−−√−5√
25+45−5

2 Simplify 45−−√45 to 35√35
25√+35√−5√
25+35−5

3 Simplify
45√