Factories:
25a2 – 4b2 + 28bc – 49c2
Given,
25a2 – 4b2 + 28bc – 49c2
= 25a2 – (4b2 – 28bc + 49c2)
By using the formula a2 – b2 = (a + b)(a – b)
We get,
25a2 – 4b2 + 28bc – 49c2 = 25a2 – (4b2 – 28bc + 49c2)
= (5a)2 – (2b – 7c)2
= {5a + (2b – 7c)}{5a – (2b – 7c)}
= (5a + 2b – 7c)(5a – 2b + 7c)