If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

College Algebra

Course: College Algebra > Unit 5

Lesson 6: Forms and features of quadratic functions
Math
College Algebra
Quadratic functions and equations
Forms and features of quadratic functions
© 2023 Khan AcademyTerms of usePrivacy PolicyCookie Notice

Interpret quadratic models

Google Classroom

Problem

Amir throws a stone off of a bridge into a river. The stone's height (in meters above the water) t seconds after Amir throws it is modeled by
h(t)=−5t2+20t+160
Amir wants to know when the stone will reach its highest point.
1) Rewrite the function in a different form (factored or vertex) where the answer appears as a number in the equation.
h(t)=
2) How many seconds after being thrown did the stone reach its highest point?
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
seconds
Stuck?
Stuck?