What is the square root of -16

-8i
-4i
4i
8i

Pls explain tooo

Angel entered a triathlon (a three-part race). he swam 1 mile, rode his bike 30 miles, and ran 10 miles. how far did he go altogether? a. 11 miles b. 123 miles c. 41 miles d. 40 miles

Iam a rectangle. my perimeter is 60 feet. how much are do i cover?

Which expression is equivalent to 3^3 + 2^2?