Respuesta :
Answer:
Rounding to the nearest hour, the times at which the population was 600,000 was at 9 hours and at 39 hours.
Step-by-step explanation:
Determine the time(s) at which the population was 600,000.
This is t for which P(t) = 600000. To do this, we solve a quadratic equation.
Solving a quadratic equation:
Given a second order polynomial expressed by the following equation:
[tex]ax^{2} + bx + c, a\neq0[/tex].
This polynomial has roots [tex]x_{1}, x_{2}[/tex] such that [tex]ax^{2} + bx + c = a(x - x_{1})*(x - x_{2})[/tex], given by the following formulas:
[tex]x_{1} = \frac{-b + \sqrt{\bigtriangleup}}{2*a}[/tex]
[tex]x_{2} = \frac{-b - \sqrt{\bigtriangleup}}{2*a}[/tex]
[tex]\bigtriangleup = b^{2} - 4ac[/tex]
In this question:
[tex]P(t) = -1718t^{2} + 82000t + 10000[/tex]
We have to find t for which P(t) = 600000. Then
[tex]600000 = -1718t^{2} + 82000t + 10000[/tex]
[tex]-1718t^{2} + 82000t - 590000 = 0[/tex]
So [tex]a = -1718, b = 82000, c = -590000[/tex]
Then
[tex]\bigtriangleup = 82000^{2} - 4*(-1718)*(-590000) = 2669520000[/tex]
[tex]t_{1} = \frac{-82000 + \sqrt{2669520000}}{2*(-1718)} = 8.8[/tex]
[tex]t_{2} = \frac{-82000 - \sqrt{2669520000}}{2*(-1718)} = 38.9[/tex]
Rounding to the nearest hour, the times at which the population was 600,000 was at 9 hours and at 39 hours.
