Ooooh these are fun! They are pretty much like multiplying binomials but with a twist.
(2 + 6i)(2 - 6i) = 2(2) + 2(-6i) + 6i(2) + 6i(-6i) = 4 -12i + 12i - 36i2 = 4 - 36i2
Now remember that i is the square root of -1. That means if we square i, we get -1, soooo...
4 - 36i2 = 4 - 36(-1) = 4 + 36 = 40
Brian P.
Another way and a shorter way is to use a popular formula (a+b)*(a-b)= (a**2-b**2) In the above problem case a=2 and b=6i Since b**2=36I**2=-36 so to get to the product of two functions = (4- (-36) = 40 . Comment: This way it is much faster and easier to get to the answer...40
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08/29/19
Kaity O.
Thank you08/26/19