If z = (3 + 7i) (a + ib) where a,b∈Z−{0}, is purely imaginary, then the minimum value of |z| is

z=(3a−7b)+i(3b+7a)For z to be purely imaginary we have3a=7b⇒a=7 or b=3 (for least value of |z| ) ⇒|z|=58

If z = (3 + 7i) (a + ib) where a,b∈Z−{0}, is purely imaginary, then the minimum value of |z| is

z=(3a−7b)+i(3b+7a)For z to be purely imaginary we have3a=7b⇒a=7 or b=3 (for least value of |z| ) ⇒|z|=58

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If z = (3 + 7i) (a + ib) where $a, b \in Z - {0}$ , is purely imaginary, then the minimum value of |z| is

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$z = (3 a - 7 b) + i (3 b + 7 a)$

For z to be purely imaginary we have

$\begin{array}{l} 3 a = 7 b \\ \Rightarrow a = 7 or b = 3 (for least value of | z |) \\ \Rightarrow | z | = 58 \end{array}$

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If z = (3 + 7i) (a + ib) where a,b∈Z−{0}, is purely imaginary, then the minimum value of |z| is

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If z = (3 + 7i) (a + ib) where $a, b \in Z - {0}$ , is purely imaginary, then the minimum value of |z| is