Question

Find |Z| where Z= (i + 2i) (3 - 4i)​

Answer 1

Answer:

15

Step-by-step explanation:

Z = ( i + 2i )( 3 - 4i )

   = 3i ( 3 - 4i)

   = 9i - 12i²

   = 9i - 12(-1) ( ∵ i² = (√-1)² = -1 )

   =  9i + 12

We know that

        $|ai+b|=\sqrt{a^2+b^2$

∴ |Z| = $|ai+b|$ = $\sqrt{a^2+b^2$ = $\sqrt{9^2+12^2}$ = $\sqrt{81+144}$ = $\sqrt{225}$ = $15$

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