Help me? Product of a sum and a difference
Formula; (a + b)(a - b) = a^2 - b^2

Find the product of the following

1. (2x - 5)(2x + 5)

2. (5b - 6y)(5b + 6y)

3. (4k + 7)(4k - 7)

4. (y - 5)(y + 5)

5. (3x - 2)(3x + 2)

6. (13x + 2x^3)(13x - 2x^3)

7. (2a + 1)(2a - 1)

8. (9y^2 + 8)(9y^2 - 8)