Answer:
-4
Explanation:
(a^2 - b^2) / a - b
The numerator a^2 - b^2 could be factored into (a + b)(a - b) because of the difference of squares formula.
(a + b)(a - b) / (a - b)
Because a - b is present in both the numerator (top part of fraction or division equation) and denominator (bottom part) in parentheses, it cancels out. So you can cross out (a - b) from both the top and bottom to get just (a + b) / 1 or just a + b.
Input 5 and -9 to get 5 + (-9) or 5 - 9. That equals -4.