Y squared + 5y - 84 equals what

The two possibilities for y are y = - 12 and y = 7.

In order to solve this, we first just factor the equation. In order to factor a quadratic like this, we look for factors of the last number (-84) that add up to the middle number (5). In order to find that, we just need to list the factors.

1 * - 84

-1 * 84

2 * - 42

-2 * 42

3 * - 28

-3 * 28

4 * - 21

-4 * 21

7 * - 12

- 7 * 12

This last factor is the one that adds to 5. Now we stick these two numbers along with y's into parenthesis.

(y - 7) (y + 12)

Now to solve, we can set each parenthesis equal to 0 to solve.

y - 7 = 0

y = 7

y + 12 = 0

y = - 12