96.4k views
3 votes
The number of new cars purchased in a city can be modeled by the equation where C is the number of new cars and t is the number of years since 1958. C = 26t^2 + 168t + 4208. In what year will the number of new cars reach 15,000? a. 2026 b. 1993 c. 1970 d. 1976 Solve using the quadratic formula. HELP PLZ!

User TJF
by
8.1k points

1 Answer

4 votes
C(t)=26t^2+168t+4208, and we wish to know when C(t)=15000

26t^2+168t+4208=15000

26t^2+168t-10792=0

They want you to use the quadratic formula...

For a quadratic of the form ax^2+bx+c=0, the quadratic formula is:

x=(-b±√(b^2-4ac))/(2a), in this case we have:

x=(-168±√1122368)/52, since x>0

x≈17.14

1958+17.14≈1975.14

So by 1976 the number of new cars will reach 15000.
User Voivoid
by
7.9k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.