Question

factorise it by a method​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

$25(a+b)^2-16(a-b)^2=\\(5(a+b)-4(a-b))(5(a+b)+4(a-b))=\\(5a+5b-4a+4b)(5a+5b+4a-4b)=\\(a+9b)(9a+b)$