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intermediate algebra
- Thread starter pebbs310
- Start date
Simplify the following prdct of complex numbers. Was wondering if I got this correct
(5+3i)*(6-2i)
5*6+5*-2i+3i*6+3i*2i
combine the like terms
30+8i+6
36+8i=answer
You had this:
5*6 + 5*(-2i) + 3i*6 + 3i*2i
You did not show the results of the individual multiplications...I'm going to do that:
30 + (-10i) + 18i + 6i2
What is the value of i2? It's -1, by definition (since i = sqrt(-1))
30 + (-10i) + 18i + 6*(-1)
30 + (-10i) + 18i + (-6)
NOW combine like terms and see what you get.
Simplify the following prdct of complex numbers. Was wondering if I got this correct
(5+3i)*(6-2i)
5*6+5*-2i+3i*6+3i*2i
combine the like terms
30+8i+6
36+8i=answer
Someone - please correct me if I have this wrong.
Pebbs310, I believe you have the right answer, but you skipped a step that may be an error.
When multiplying the last two terms "3i" and "-2i" you write that the result is "+3i*2i". This is not correct. You then later write "+6" which IS correct.
The correct result is "5*6+5*-2i+3i*6 - 3i*2i"
30 - 10i + 18i -6i^2
30 + 8i - (6(-1))
30 + 8i - (-6)
30 + 8i + 6
36 + 8i
Therefore, I'm not sure if you made a mistake, but got lucky and got the right answer, or if you were aware that i^2 = -1 and took this into account when you changed the sign of the last term. I suspect the latter.
At the least, I hope my steps will serve to show others how you arrived at your answer.