• Feb 21st 2009, 02:30 AM
alpharebel10
the question is
z = (2-i)
w=(5+3i)
so work out
a)zw
b)z/w
both of which i can do with no problem but the last bit is
c) |w|
can some one please tell me what the 2 straight lines mean on each side of the w thank you 4 ur time and any help

also im a bit stuck with this simultaneous equation i have never done them with fractions in i think it is easy but i might just be looking at it in the wrong way
4/x+1/y=5/3
1/x-3/y=3/2
should i be trying to get it on 1 line so times it by xy any help would be very greatfull thank you
• Feb 21st 2009, 02:50 AM
earboth
Quote:

Originally Posted by alpharebel10
the question is
z = (2-i)
w=(5+3i)
so work out
a)zw
b)z/w
both of which i can do with no problem but the last bit is
c) |w|
can some one please tell me what the 2 straight lines mean on each side of the w thank you 4 ur time and any help

|w| is the absolute value of w

Quote:

also im a bit stuck with this simultaneous equation i have never done them with fractions in i think it is easy but i might just be looking at it in the wrong way
4/x+1/y=5/3
1/x-3/y=3/2
...
Set $r = \frac1x$ and $s = \frac1y$ then your system of equations becomes:

$\left|\begin{array}{l}4r+s=\frac53 \\r-3s=\frac32\end{array}\right.$

Solve for r and s and re-substitute to calculate x and y.
• Feb 21st 2009, 03:58 AM
james_bond
Quote:

Originally Posted by alpharebel10
c) |w|
can some one please tell me what the 2 straight lines mean on each side of the w thank you 4 ur time and any help

See here.