My question is a complex numbers question: square root - 6 times square root - 24 the answer is - 12, but I don't know how to solve it

see below

Step-by-step explanation:

sqrt (-6) * sqrt (-24)

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

sqrt (6) sqrt (-1) * sqrt (24) sqrt (-1)

We know that sqrt (-1) = i

sqrt (6) i * sqrt (24) i

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

sqrt (6*24) i*i

sqrt (144) i^2

12 i^2

We know that i^2 = - 1

12 (-1)

-12