SOLUTION: Write the following expressions as a complex number in standard form. {{{(-1+5i)/(3+7i)}}}

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Question 315483: Write the following expressions as a complex number in standard form.
%28-1%2B5i%29%2F%283%2B7i%29

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Write the following expressions as a complex number in standard form.
%28-1%2B5i%29%2F%283%2B7i%29

Form the conjugate of 3%2B7i by changing the sign of the term
containing i and leaving the sign of the first term.

Thus the conjugate of 3%2B7i is 3-7i.

Place that conjugate over itself, like this %28%283-7i%29%2F%283-7i%29%29,
which just equals 1, and so we can now multiply the original
expression by that without changing its value:

%28%28-1%2B5i%29%2F%283%2B7i%29%29%28%283-7i%29%2F%283-7i%29%29

%28+%28-1%2B5i%29%283-7i%29+%29+%2F+%28+%283%2B7i%29%283-7i%29+%29

Using FOIL on top and bottom:

+%28-3%2B7i%2B15i-35i%5E2%29%2F%289-21i%2B21i-49i%5E2%29

Combining like terms (the middle terms cancel in the bottom)

+%28-3%2B22i-35i%5E2%29%2F%289-49i%5E2%29

Replace i%5E2 by -1

+%28-3%2B22i-35%28-1%29%29%2F%289-49%28-1%29%29

Simplify:

+%28-3%2B22i%2B35%29%2F%289%2B49%29

+%2832%2B22i%29%2F58

Make two fractions, and write the i as multiplied on the right of
the second fraction, so it will be in the standard form A%2BBi:

32%2F58%22%2B%2222%2F58i

Reduce the fractions

16%2F29%22%2B%2211%2F29i

Edwin