Question

Factorise 25a2-b2+28bc-49c2​

Answer 1

Answer:

(5a – 2b + 7c)(5a + 2b – 7c)

Step-by-step explanation:

25a2 – 4b2 + 28bc – 49c2

= (5a)2 – (4b2 – 28bc + 49c2)

= (5a)2 – {(2b)2 – 2(2b)(7c) + (7c)2}

= (5a)2 – (2b – 7c)2

= (5a – 2b + 7c)(5a + 2b – 7c)