#### (i) (3p – 4q) (9p^{2} + 12pq + 16q^{2})

#### (ii) (x – 3/x) (x^{2} + 3 + 9/x^{2})

**Answer :**

**(i) (3p – 4q) (9p**^{2} + 12pq + 16q^{2})

^{2}+ 12pq + 16q

^{2})

It can be written as

= (3p – 4q) [(3p)^{2} + 3p × 4q + (4q)^{2}]

By further simplification

= (3p)^{3} – (4q)^{3}

= 27p^{3} – 64q^{3}

**(ii) (x – 3/x) (x**^{2} + 3 + 9/x^{2})

^{2}+ 3 + 9/x

^{2})

It can be written as

= (x – 3/x) [x^{2} + x × 3/x + (3/x)^{2}]

By further simplification

= x^{3} – (3/x)^{3}

= x^{3} – 27/x^{3}

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