Question

Which expression is equal to 4√20 - 3√45

A.11√5

B.−11√5

C.√5

D.−√5

Answer 1

D.−√5

Explanation:

4 sqrt(20) -3 sqrt(45)

We know that sqrt(ab) = sqrt(a) sqrt(b)

4 sqrt(4) sqrt(5) - 3 sqrt(9) sqrt(5)

4 *2 sqrt(5) - 3 *3 sqrt(5)

8 sqrt(5) - 9 sqrt(5)

- sqrt(5)