find each pair of complex numbers..?

Question

..and their sum in the complex plane, find their magnitudes. 5i, -i

i meant plot each pair of complex # and their product in the complex plane. find their magnitudes. sorry. a bit out of it =|

Answer 1

OK. I'm confused. I only see two imaginary numbers.

Maybe there's something you left out???


Doug

Answer 2

I'm not sure exactly what you want here.

5i + (-i) = 4i, of course. Since these are all pure imaginary, the magnitudes are easy:
||5i|| = 5, ||-i|| = 1, ||4i|| = 4.
In general, ||ki|| = |k| for any real number k.

If you have a complex number a + bi (a and b real), then the magnitude is √(a^2 + b^2). If your complex number is expressed in polar form as r.e^(iθ), where r and θ are real and r >= 0, the magnitude is r.