If $\dfrac { { a }^{ 2 }-\dfrac { 1 }{ { b }^{ 2 } } }{ { b }^{ 2 }-\dfrac { 1 }{ { a }^{ 2 } } } =9$, then what is the value of $\left| \dfrac { a }{ b } \right|$?

and
$\left| ab \right| \neq 1$

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