SOLUTION: write in a+bi form 1). {{{(4+5i)/(6+i)}}} 2). {{{14/i}}}

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: write in a+bi form 1). {{{(4+5i)/(6+i)}}} 2). {{{14/i}}}      Log On


   



Question 315734: write in a+bi form
1). %284%2B5i%29%2F%286%2Bi%29
2). 14%2Fi

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Write the following expressions as a complex number in standard form.
1). %284%2B5i%29%2F%286%2Bi%29

Form the conjugate of 6%2Bi by changing the sign of the term
containing i and leaving the sign of the first term.

Thus the conjugate of 6%2Bi is 6-i.

Place that conjugate over itself, like this %28%286-i%29%2F%286-i%29%29,
which just equals 1, and so we can now multiply the original
expression by that without changing its value:

%28%284%2B5i%29%2F%286%2Bi%29%29%28%286-i%29%2F%286-i%29%29

%28+%284%2B5i%29%286-i%29+%29+%2F+%28+%286%2Bi%29%286-i%29+%29

Using FOIL on top and bottom:

+%2824-4i%2B30i-5i%5E2%29%2F%2836-6i%2B6i-i%5E2%29

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

+%2824%2B26i-5i%5E2%29%2F%2836-i%5E2%29

Replace i%5E2 by -1

+%2824%2B26i-5%28-1%29%29%2F%2836-%28-1%29%29

Simplify:

+%2824%2B26i%2B5%29%2F%2836%2B1%29

+%2829%2B26i%29%2F37

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:

29%2F37%22%2B%2226%2F37i

---------------

2). 14%2Fi

You only need to multiply that by i%2Fi

%2814%2Fi%29%28i%2Fi%29

%2814i%29%2Fi%5E2

Replace the i%5E2 by -1

%2814i%29%2F%28-1%29

-14i

Edwin