Answer:
Step-by-step explanation:
P(d) ≥ 8000
P(d) = - 5d^2 + 450d - 1000 ≥ 8000 Subtract 8000 from both sides
-5d^2 + 450d - 1000 - 8000 ≥ 0 Combine like terms
-5d^2 + 450d - 9000 ≥ 0 Divide through by - 5
d^2 - 90d + 1800 ≥ 0 Factor
(d - 60)(d - 30)
So d ≥ 60
or d ≥ 30
So if customers make more than 30 downloads, the profit goes up 8000.
