SAT Question Involving i

Question

For i = √−1 , what is the sum (7 + 3i) + (−8 + 9i)?

Answer 1

The SAT usually contains ONLY ONE question involving complex numbers and it's often super basic. Many students see the square root of negative one and immediately say "I never learned this," and they bubble in a random answer and keep going (because math is terrifying). But even if you don't know that complex numbers are numbers containing a real part "a" and an imaginary part "b", ie (a + bi), you can easily just combine like terms:

problem = (7 + 3i) + (-8 + 9i)

combine 7 and -8 -------------> 7 + -8 = -1

then combine 3i and 9i ------> 3i + 9i = 12i

answer = -1 + 12i

Wayyyyy easier than you thought it was! The only other thing you would need to know is that the word "sum" means addition. This will be important for English Language Learners :)