Abit of help

PowerHouseDan

I need to learn how to do some complex numbers i need a sample question to go from.
anyone able to help.
|z1 + z2| where z1 =10-10i
and z2 =10-11i

and (i+i)squared

Crumbs

z1+z2 = (10-10i) + (10-11i) = 20-21i

|z1+z2| = sqrt[(20)^2 + (-21)^2]
= sqrt[400 + 441]
= sqrt[841]
= 29



(i+i)^2 = (2i)^2 = 4i^2 = 4(-1) = -4

PowerHouseDan

cheers i managed to get the hang of polar form. now all i have left is a argand but no point postin a question cos cant be drawn thanks for your help

ecksor

Hard to draw, but you can deal with the angle and magnitude with a bit of notation to answer any questions so it might be worth posting.

PowerHouseDan

ok. Well here is the First
Clearly Label and properly scaled to show the positions of the following.

z=-3 +4i


and

2Z1 + 3z2 where z1 = 3+6i
and z2 = -4-5i

and

z=-3+4i

ecksor

Do you not just have to calculate what those expressions evaluate to and then plot them on the complex plane?

PowerHouseDan

maybe?i havent done them before

dudara

Just draw two axes. The horizontal one is for real numbers and the vertical is for complex numbers.

to plot 2(z1) + 3(z2) = -6 - 3i, go to the left of the origin 6 units, and then down 3 units. Draw a line from the origin to that point.

isn't that it? it's been a while since I did it too.

ecksor

Sounds fine to me.