Question #2b052

1 Answer
Dwight
Oct 18, 2017

The answer is 5.

Explanation:

This is an example of two factors that are complex conjugates . The two binomials have the same real and imaginary parts, but one is a sum while the other is a difference of terms.

The result is always a real number.

(It's similar to #(x+2)(x-2) = x^2 - 2^2#)

Use the FOIL method as you would for any other binomial:

#2*2 + 2*i - 2*i -i^2 #

The second and third term cancel, leaving

#4-i^2#

Since #i^2=-1# the value is #4+1=5#

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