An online music service that sells song downloads models it's profit using the function p(d)=-5d^2+450d-1000, where d is the number of downloads sold and p is the profit. how many downloads does it need to sell to make a profit of more than $8000?

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.

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.

you save $70

discount would be 35% off

step-by-step explanation: