(7a 2 – 63b 2 ) = 7(a 2 – 9b 2 ) (taking 7 as common from whole) = 7(a – 3b)(a + 3b) a 2 – b 2 = (a – b)(a + b)

(7a 2 – 63b 2 ) =?

(7a² – 63b²) = 7(a² – 9b²) (taking 7 as common from whole)

= 7(a – 3b)(a + 3b) a² – b² = (a – b)(a + b)