How would you factorise 15n - 1?

Answer 1

14

Answer 2

It is difficult, if not impossible, to entirely factorise a purely algebraic expression, however, using the difference of two squares:

15n - 1 = a2 - b2
a2 - b2 = (a+b)(a-b)

So, 15n - 1 = (a+b)(a-b).
a = √(15n)
b = √1 = 1

∴ 15n - 1 = (√(15n)+1)(√(15n)-1).