A^2+5a-24=0 solve the equation by factoring

(a + 8)(a - 3)
You should think about what numbers multiply together to give -24 but add together to give you +5. 

According to his answer above, the factor is (a+8)(a-3). To solve for a, we could see what can give 0 when we multiply the factor. In (a-3), 3 can be subtracted by 3 which is 0, then is being multiplied by another factor, which is still 0. So let's plug 3 as a in our equation. 3^2+5(3)-24=0 is 9+15-24. Simplify. 9+15-24 is 0, so 3 can be an answer to our equation. Now let's see what can we add in (a+8) to get 0. That is -8, because -8+8=0. Now let's try in our equation. -8^2+5(8)-24 is 64+40-24. Simplify. 84-24 which is 60. So -8 can not be a possibility. Therefore 3 is the only answer.

Real a=3