1/49149 is the same as (1^2/7^21272). 1/49149 and x^2x2 are both perfect squares so we use the difference of squares (factoring).
(a^2 - b^2) = (a + b) * (a - b)(a2−b2)=(a+b)⋅(a−b)
If you 'foil' the answer, you get (a^2 - ab +ab - b^2)(a2−ab+ab−b2). (-ab)(−ab) and (+ab)(+ab) cancel, resulting in the original (a^2 - b^2)(a2−b2).
For the problem, the same process applies:
1. (1/49 - x^2)(149−x2)
2. (1/7 + x) * (1/7 - x )(17+x)⋅(17−x)
To check, [(1/7 * 1/7) - (1/7)x + (1/7)x - (x*x)] = (1/49 - x^2)[(17⋅17)−(17)x+(17)x−(x⋅x)]=(149−x2)
