Question #b1685

2 Answers
Dec 14, 2016

sqrt8*sqrt20

=sqrt(2^2*2)*sqrt(2^2*5)

=2sqrt2*2sqrt5

=4sqrt(2*5)

=4sqrt(10)

Dec 14, 2016

4sqrt(10)

Explanation:

Since sometimes students have trouble with exponents, another way to look at this question is to factor the number under the radical where one of the factors is a perfect square.
sqrt(8)*sqrt(20)=sqrt(4*2)*sqrt(4*5)
color(white)(aaaaaaaa)=sqrt(4)sqrt(2)*sqrt(4)sqrt(5)
color(white)(aaaaaaaa)=2sqrt(2)*2sqrt(5)
Then multiply the coefficients together separately and the numbers under the roots separately.
color(white)(aaaaaaaaa)=(2)(2)sqrt(2*5)
color(white)(aaaaaaaaa)=4sqrt(10)