Answer:
Step-by-step explanation:
P = 1800 + 700x - 100x²
Find x when p = $2,800
2,800 = 1800 + 700x - 100x²
- 100x² + 700x + 1800 - 2800 = 0
-100x² + 700x - 1000 = 0
- x² + 7x - 10 = 0
a = -1
b = 7
c = -10
x = -b ± √b² - 4ac / 2a
x = -7 ± √7² - 4(-1)(-10) / 2(-1)
= -7 ± √49 - 40 / -2
= -7 ± √9 / -2
= -7 ± 3 / -2
= (-7 + 3) / -2 or (-7 - 3) / -2
= -4 / -2 or -10 / -2
x = 2 or 5
x = 2 items for smaller value
x = 5 items for larger value
