(3-i) (-6 + i)
2007-07-08 15:13:48 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Use the FOIL method to expand:
(3-i) (-6 + i)
= -18 + 3i + 6i - i^2
= -18 + 9i + 1 (since i^2 = -1)
= -17 + 9i
2007-07-08 15:18:23 · answer #1 · answered by triplea 3 · 1⤊ 0⤋
Use the foil method to get -18 + 6i + 3i +1 = -17 + 9i
2007-07-08 22:20:11 · answer #2 · answered by steiner1745 7 · 0⤊ 0⤋
Use the old FOIL trick: First, Outside, Inside, Last
(3-i)(-6+i)= 18(F) +3i(O) +6i(I) -i^2(L)
=18 +9i +1
=19 + 9i
The tricky part is -i^2. Write this as -1(i^2)
i=rt(-1), so i^2 is (rt-1)(rt-1), which is -1.
We thus get -1(-1), =+1
2007-07-08 22:36:53 · answer #3 · answered by Grampedo 7 · 0⤊ 0⤋
(3-i)(-6+i)
= -18 + 3i +6i - i^2
= -18 + 9i - i^2
= -18 + 9i + 1
= -17 + 9i
2007-07-08 22:21:13 · answer #4 · answered by James V 2 · 0⤊ 0⤋
I love these!
FOIL
3*-6=-18
3*i=3i
-i*-6=6i
-i*i=-i^2
-18+3i+6i-i^2
-18+9i+1
=9i-17
2007-07-08 22:19:58 · answer #5 · answered by Shauna 3 · 0⤊ 2⤋