Question

If A = -3 + 5i, B = 4 - 2i, and C = 1 +6i, where i is the imaginary unit, then A - BC equals

Answer 1

Answer:

3) -19 - 17i is our answer

Step-by-step explanation:

to solve A - BC we plug in the values given

A= -3 + 5i

B = 4 - 2i

C = 1 + 6i

-3 + 51i - (4 - 2i)(1 + 6i) is our expression. we can FOIL (4 - 2i)(1 + 6i) this expression out. FOIL stands for:

First

Outside

Inside

Last

i will highlight the terms i am using in the current step in bold and put the result next of those two terms next to the expression

F: (4 - 2i)(1 + 6i) = 4

O: (4 - 2i)(1 + 6i) = 24i

I: (4 - 2i)(1 + 6i) = -2i

L: (4 - 2i)(1 + 6i) = 12 < --- the reason why its 12 and not -12i or 12i is because i = √-1 and i² = -1

when we multiply -2i * 6i, we would have gotten a -12i², and i² = -1, so we are multiplying -12 by -1, which gives us 12 as the result

combining all these terms together and we have:

4 + 24i - 2i + 12

in the expression this is:

-3 + 5i - (4 + 24i - 2i + 12) < we need to distribute the negative sign into (4 + 24i - 2i + 12) and we now get:

-3 + 5i -4 - 24i + 2i - 12 < combine like terms (ex: i terms together)

-3 - 4 - 12 = -19

5i - 24i + 2i = -17i

the result of the expression is:

-19 - 17i

we cannot simplify this any further so this is our answer. the answer choice that matches this is 3, so 3) -19 - 17i is our answer