Answer
$|10-7i|=\sqrt{149}$
Work Step by Step
The absolute value of a complex number
$z=a+bi,$ denoted $|z|,$ is a nonnegative
real number defined as $|z|=\sqrt{a^{2}+b^{2}}$.
$|z|=|10-7i|$
$=\sqrt{a^{2}+b^{2}}\qquad$ ...substitute $10$ for $a$ and $-7$ for $b$
$=\sqrt{10^{2}+(-7)^{2}}\qquad$ ...simplify.
$=\sqrt{100+49}$
$=\sqrt{149}$