Whats the square root of negative 8 times the square root of negative 10?

Question

2693 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-09-22T02:19:43

This is written as:

#sqrt(-8)sqrt(-10)#

What you can do is factor out the two #sqrt(-1)# and multiply them, canceling the square root, but not changing the sign of the number under it:

#sqrt(-8)sqrt(-10) = sqrt(-1)*sqrt(8)*sqrt(-1)*sqrt(10)#

#= -sqrt(80)#

#= -sqrt(16*5)#

#= color(blue)(-4sqrt5)#