Factories: 81

We have, 81 – 49x 2 = (9) 2 – (7x) 2 By using the formula a 2 – b 2 = (a + b)(a – b) We get, 81 – 49x 2 = (9) 2 – (7x) 2 = (9 + 7x)(9 – 7x)

We have,

81 – 49x²

= (9)² – (7x)²

By using the formula a² – b² = (a + b)(a – b)

We get,

81 – 49x² = (9)² – (7x)²

= (9 + 7x)(9 – 7x)