Question

25(a-b)的2次方-16(a+b)的平方

Answer 1

25(a-b)的2次方-16(a+b)的平方

=(5(a-b))^2-(4(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)