Answer:
x^2 +3x -504
Step-by-step explanation:
Sort of do what you'd do to solve but in reverse. You need 21 for a zero, so the binomial factor would be (x-21) since if you set that = to zero you'd get 21. Same for -24. The binomial factor would be (x+24) since that would give you -24. Now that you have the two binomials, you can just multiply them and get the quadratic. :)
