Multiply (5-3i)(3+6i). I heard my sub say that we're supposed to use "FLOI" when there's complex numbers and I have a test tomorrow. I need to confirm whether or not if its FOIL or FLOI so help someone, please. =]
2006-11-01 16:03:26 · 19 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
F, O, I, and L are all products.
Because you are adding them, it does not matter what order you add them in. (i.e., FOIL = FLOI)
2006-11-01 16:06:25 · answer #1 · answered by topher8128 2 · 3⤊ 1⤋
Actually, it doesn't really matter. The point of FOIL FLOI, OILF, etc. is simply to make sure that the products of all four terms in the parentheses are calculated and summed.
Works exactly the same as multiplying out a polynomial.
(x+3)(4x-1) = 4x^2+11x-3
2006-11-01 16:07:44 · answer #2 · answered by Guru 6 · 3⤊ 0⤋
Its Foil, or learn it like this, "the rainbow method" just mulitply 5 x 3, 5 x6i, then -3i x 3, and 3i x 6i
2006-11-01 16:06:37 · answer #3 · answered by venom90011@sbcglobal.net 1 · 0⤊ 0⤋
it really doesn't matter the order in which you do this as long as you make sure you don't leave anything out... I think that she might be telling you FLOI because the first and last will end up with real numbers and the outer and inner will give you imaginary numbers. when you multiply them together you will end up with something like 15+18+30i-9i then 33+21i. most people like to see the real number first then the imaginary. do it whichever way you feel most comfortable with then put it in standard form.
2006-11-01 16:15:41 · answer #4 · answered by fleisch 4 · 0⤊ 0⤋
FOIL Method
(5 - 3i)(3 + 6i)
First
3 x 5 = 15
Outer
3i x 3 = 9 i
Inner
6i x 5 = 30i
Last
6i x 3i = 18i²
- - - - - - - - - - -
(5 - 3i)(3 + 6i) = 15 - 9i + 30i - 18i² = 5 - 21i - 18i²
- - - - - - - - - -s-
2006-11-01 20:52:40 · answer #5 · answered by SAMUEL D 7 · 0⤊ 0⤋
It's FOIL (First, Outside, Inside, Last)
2006-11-01 16:11:01 · answer #6 · answered by Anonymous · 0⤊ 0⤋
never heard of FLOI. It's FOIL.. don't worry about the test! You'll do fine, I have one tomorrow too... Good luck!
2006-11-01 16:06:48 · answer #7 · answered by MysteryMan 1 · 0⤊ 0⤋
Umm honey i think it is FOIL(first outer inner last) not FLOI that just sounds crazy
2006-11-01 16:09:49 · answer #8 · answered by lil_mama1837 1 · 0⤊ 0⤋
Multiplying complex numbers is the same as multiplying polynomials. => 15 + 30i - 9i - 18i^2 = 15 + 21i + 18 = 33 + 21i
2006-11-01 16:15:48 · answer #9 · answered by Anonymous · 0⤊ 0⤋
It's FOIL
F-First
O-Outer
I-Inner
L-Last
Step 1:
F-First
(5-3i)(3+6i)
5 x 3
Step 2:
O-Outer
(5-3i)(3+6i)
5 x 6i
Step 3:
I-Inner
(5-3i)(3+6i)
-3i x 3
Step 4:
L-Last
(5-3i)(3+6i)
-3i x 6i
2006-11-01 16:17:35 · answer #10 · answered by Anonymous · 0⤊ 0⤋