# Thread: Complex number problem...

1. ## Complex number problem...

two complex numbers: z and w are given by
z = 5.2 - 3.4j
w = 1.6 + 4.2j

(i) find z + w, zw and z/w.

(ii)
find z - w, express this in polar form and plot it on an Argand Diagram.

Any workings for the first part will be greatly recieved, and any help for second will be a bonus
Thankss...

2. Originally Posted by mucky
two complex numbers: z and w are given by
z = 5.2 - 3.4j
w = 1.6 + 4.2j

(i) find z + w, zw and z/w.

(ii)
find z - w, express this in polar form and plot it on an Argand Diagram.

Any workings for the first part will be greatly recieved, and any help for second will be a bonus
Thankss...
just remember that $(a+bi)\pm(c+di)=(a\pm{b})+(ci\pm{di})$

3. Originally Posted by mucky
two complex numbers: z and w are given by
z = 5.2 - 3.4j
w = 1.6 + 4.2j

(i) find z + w, zw and z/w.
Add like plus like:
$(a + jb) + (c + jd) = (a + c) + (b + d)j$

wz: Just FOIL it out. And remember that $j^2 = -1$.

z / w: Hint: rationalize the denominator. aka multiply the numerator and denominator by the complex conjugate of the denominator.

-Dan