Simplify (6 - 2i)(-3 + 4i)?

👨🏻‍🏫 學術台數學

[匿名]

2009-03-24 3:20 pm

I've tried 'FOIL', which is what i thought you was supposed to do, but i cant seem to come out with the right anwser? Maybe im FOILing wrong?

更新1:

I got the same thing you got cyber, but that is not the correct answer :/

更新2:

never mind, i forgot to finish the problem all the way out, thanks :)

回答 (4)

[匿名]

2009-03-24 3:24 pm

✔ 最佳答案

-18 + 24i + 6i + 8

= 30i - 10

Note: i² = -1

I did this on a calculator and it showed this answer. Any idea why it is wrong?

Unless you are looking for :

-18 + 24i + 6i - 8i² = -8i² + 30i - 18

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An ESL Learner

2009-03-24 3:43 pm

(6 - 2i)(-3 + 4i)
= 6*-3 + 2i*3 + 6*4i - 2i*4i
= -18 + 6i + 24i - 8i^2
= -18 - 8(-1) + 30i
= -18 - (-8) + 30i
= -18 + 8 + 30i
= -10 + 30i

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Engr. Ronald

2009-03-24 3:30 pm

If you post your solution in your question, we can check it.
Well here is the solution for your problem.

(6 - 2i)(-3 + 4i)
=-18+24i+6i-8i^2
=-18+24i+6i-8(-1)
=-18+24i+6i+8
=30i-10 answer//

參考: check my answer here: http://www.myalgebra.com/algebra_solver.aspx

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[匿名]

2009-03-24 3:27 pm

(6 - 2i)(-3 + 4i) = -18 + 24i + 6i - 8i^2

[# Now, depending on if this is a complex number equation or a normal equation, it will go like this.]

Normal equation: -8i^2 + 30i - 18

Complex number equation: 30i -18 + 8 = 30i - 10

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