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Moderate

Length of a Complex Number

ACTMAT-FN9G0J

If $z = a+bi$, then:

$$|z| = \sqrt { { a }^{ 2 }+{ b }^{ 2 } } $$

Which of the following is equal to $|z|$ if$ z = -8+15i $?

A

$7$

B

$120$

C

$-7$

D

$23$

E

$17$