Answer:
[tex](a)\ t^2 - 20t + 75= 0[/tex]
[tex](b)[/tex] [tex]t = 5; t -=15[/tex]
Step-by-step explanation:
Given
[tex]p(t) = t^2 - 20t + 175[/tex]
Solving (a): Equation when profit = 100.
This implies that:
[tex]p(t) =100[/tex]
So, we have:
[tex]100 = t^2 - 20t + 175[/tex]
Rewrite as:
[tex]t^2 - 20t + 175 - 100 = 0[/tex]
[tex]t^2 - 20t + 75= 0[/tex]
Solving (b): Calculate t, in (a)
In a, we have:
[tex]t^2 - 20t + 75= 0[/tex]
Expand
[tex]t^2 - 15t -5t + 75= 0[/tex]
Factorize
[tex]t(t - 15) -5(t - 15)= 0[/tex]
Factor out t - 15
[tex](t - 5)(t - 15)= 0[/tex]
Split
[tex]t - 5 = 0; t - 15 =0[/tex]
Solve
[tex]t = 5; t -=15[/tex]
The prices are $5 and $15, respectively