Can You Multiply Square Roots of Negative Numbers?

[dnt]

suppose you have square root of -16 times square root of -25 (in separate square root symbols).

would the answer be:

a) no solution - can't have negative square roots

b) 4i times 5i which equals 20i^2 which is -20

c) -16 times -25 which is +400, then the square root of that is 20

which one is correct?

 

[Dale]

Exponentiation has a higher precedence than multiplication, just like multiplication has a higher precedence than addition. You therefore have to evaluate the roots before evaluating the multiplication.

-Dale

 

[dnt]

so it should be choice b?

 

[HallsofIvy]

Assuming you are using the principle roots, yes.