Answer
$|z|=\sqrt{58}$
see graph below
.
Work Step by Step
See p. 602, Graphing Complex Numbers
The complex plane is determined by the real axis and the imaginary axis.
To graph the complex number a + bi, we plot the ordered pair of numbers (a,b) in this plane
See p. 603,
The modulus (or absolute value) of the complex number $z=a+bi$ is
$|z|=\sqrt{a^{2}+b^{2}}$
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$z=7-3i$
Plot $(a,b)=(7,-3)$ in the complex plane (see image).
$|z|=\sqrt{7^{2}+(-3)^{2}}=\sqrt{49+9}=\sqrt{58}$
