Question

What is the standard form of (1 + 7i)(3 − i)?

Answer 1

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Answer 2

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Answer 3

This is easy. All you need to know is that 'i' squared equals minus one.

i^2 = -1

Also, remember that the standart form of a complex number looks like this:

Z = x + yi

Now, let's do the math.

(1 + 7i)(3 − i) = 3 - i + 21i - 7i^2 = 3 + 20i - 7 * (-1) = 3 + 20i + 7 = 10 + 20i

And there you go.

The answer is: 10 + 20i