What is the sum of √-2 and √-18

a. 4 √2
b. 4 √2i
c. 5 √2
d. 5 √2i

First, it is necessary to take out the i from the root. This is done by factoring out -1 as follows, using the relation √(-1) : = i

√-2 = √(-1)(2) = i√2
√-18 = √(-1)(2)(9) = 3i√2

Simplifying by adding the two terms together:
i√2 + 3i√2 = 4i√2

Therefore the answer is B.