Algebra II:  Exploring Quadratic Functions and Inequalities

 The Quadratic Formula and the Discriminant

by: Christina M.

The Quadratic Formula is used to answer this problem:

X= -b +/- b²-4ac ÷ 2a

    A bicyclist is cycling at 20 meters per second (m/s) and accelerating at -10 m/s².  After riding for 20 m, the cyclist completely stops the bike.  How long did it take for the cyclist to stop the bike?  The equation 20= 20t - (10/2)t² can be applied to help solve this problem.  T is the time it takes to stop.  

STEP 1- write the equation in standard form=

 -(10/2)t² +20t -20 = 0

STEP 2- use the quadratic formula to substitute=

  a= -10/2, b= 20, c= -20

 T= -20 +/- (20)² -4(-10/2)(-20) ÷ 2(-10/2)

 T= -20 +/- 0 ÷ -10

 T= 2

It took 2 seconds to stop the bike.

A math link to more problems is: glencoe.com/sec/math/algebra/algebra2/algebra2_03/extra_examples/chapter6/lesson6_5.pdf

Character Education Quotation:  

I believe that every right implies a responsibility; every opportunity, an obligation; every possession, a duty.
  -- John D. Rockefeller Jr.

theotherpages.org/quote291.html

 In order for someone to be trusted with responsibility, they must be responsible.  Something good always comes with the bad.

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