Question

Subtract the complex numbers: (-2 + 12i) - (-1 - 9i)

A) -1 + 3i
B) -3 + 3i
C) -1 + 21i
D) -3 + 21i

Answer 1

B. -3 + 3i

Explanation:

Using the foil method:

-2 - 1 = -3

12i - 9i = 3i

= -3 + 3i

Answer 2

9514 1404 393

Answer:

C) -1 +21i

Explanation:

For many purposes, "i" can be treated as though it is a variable. Collect terms in the usual way.

(-2 +12i) -(-1 -9i) . . . . given

= -2 +12i +1 +9i . . . . use the distributive property to eliminate parentheses

= (-2+1) +(12i +9i) . . . group like terms

= -1 +21i