# 7.Perform the indicated operation and write the answer in standard form. a) (-2+2¡)-(-3-¡) b) -5-3¡÷3+4¡?

### 1 Answer

- RaymondLv 74 weeks ago
I suspect that your "¡" means the same thing as our "i" (the "imaginary" number such that i^2 = -1)

(-2 + 2i) - (-3i)

distribute the minus sign into the last bracket

(-2 + 2i) + 3i

add real with real, and imaginary with imaginary

-2 + 5i

This is a Complex numner (a mix of real and imaginary) where the real part is equal to -2 and the imaginary part is equal to +5

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(-5 - 3i) / (3 + 4i)

This is a bit trickier.

You must multiply above and below by the value "1" written as the conjugate of the denominator over itself.

1 = (3 - 4i) / (3 - 4i)

Something divided by itself is always equal to 1 (except 0/0 -- but in this case, 3 - 4i is not equal to zero)

(-5 - 3i) / (3 + 4i) = (-5 - 3i) / (3 + 4i) * "1"

(-5 - 3i)(3 - 4i) / (3 + 4i)(3 - 4i) =

(-15 + 20i -9i + 12i^2) / (9 - 16i^2) =

Using i^2 = -1

(-15 - 12 + 11i) / (9 + 16) =

(-27 + 11i) / 25

One (of many) standard form is

(27/25) + (11/25)i

or

1.08 + 0.44i