SOLUTION: I am having trouble with a problem in my book it reads: Find the product of each complex number and it's conjugate 8-2i I looked in my book and the answer is 68 but I want t

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: I am having trouble with a problem in my book it reads: Find the product of each complex number and it's conjugate 8-2i I looked in my book and the answer is 68 but I want t      Log On


   

Question 684089: I am having trouble with a problem in my book it reads:
Find the product of each complex number and it's conjugate
8-2i
I looked in my book and the answer is 68 but I want to know how it got it
I know I is imaginary and it equals the square root of -1
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
The conjugate si 8+2i;
therefore,
(8-2i)(8+2i)
FOIL
8(8) + 8(2i) + -2i(8) + -2i(2i)
64 + 16i - 16i - 4i^2
...
Knowing i^2 = sqrt%28-1%29%5E2+=+-1
...
64 - 4(-1)
64 + 4 = highlight_green%2868%29
.....................
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