#### (i) (7p + 9q) (7p – 9q)

#### (ii) (2x – 3/x) (2x + 3/x)

**Answer :**

**(i) (7p + 9q) (7p – 9q)**

It can be written as

= (7p)^{2} – (9q)^{2}

= 49p^{2} – 81q^{2}

**(ii) (2x – 3/x) (2x + 3/x)**

It can be written as

= (2x)^{2} – (3/x)^{2}

= 4x^{2} – 9/x^{2}

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