how to factor that polynomial

This polynomial can be factored using difference of squares.
This polynomial is in the form of a^2 - b^2 = (a + b)(a - b)
Because 1 * 1 = 1, we can use this formula to simplify this polynomial.
1 - 25y^2 = (1 + 5y)(1 - 5y)
We can use FOIL to verify this.
(1 + 5y)(1 - 5y)
1 - 5y + 5y - 25y^2
1 - 25y^2