Parabolic Investigation

2176 Words5 Pages

In this portfolio task I have investigated the patterns in the intersection of parabolas and various lines. I have formed a conjecture to find the value of D of the parabolas, which are intersected by 2 lines, of varying slopes and shown the proof of its validity. I have used the TI-84 graphic display calculator, the software Geoegebra and Microsoft Excel to do my calculations.

I have even investigated the values of D, for polynomials of higher powers and tried to come up with a general solution for all equations. I have been able to do this portfolio from the knowledge learnt from classroom discussions and through various other resources.

Question 1

“Consider the parabola y = (x−3)2 + 2 = x2−6x+11 and the lines y=x and y=2x.

(a) Using technology find the four intersections illustrated on the right.

(b) Label the x-values of these intersections as they appear from left to right on the x-axis as x1 , x2 , x3 , and x4 .

(c) Find the values of x2 – x1 and x4 – x3 and name them respectively SL and SR .

(d) Finally, calculate D = | SL − SR|”

SOLUTIONS:

Graphical Method -

Using the software Geogebra, the following graph for f(x), g(x) and h(x) is obtained –

From the graph, we can get to know that the line g(x) = x , intersects the parabola f(x) at points P (2.38,2.38) and O (4.62,4.62) , and the line h(x) = 2x intersects f(x) at points N (1.76, 3.53) and M (6.24, 12.47).

The points X1, X2, X3, and X4 have been plotted on the graph.

SL = X2 − X1

= 2.38 − 1.76

= 0.62

SR = X4 − X3

= 6.24 – 4.62

= 1.62

D = |SL − SR|

= |0.62 – 1.62|

= |-1|

= 1

THEORITICAL METHOD -

f(x) = (x−3)2 + 2

= x2 – 6x + 11

g(x) = x

Since, f(x) is inte...

... middle of paper ...

... the value of D will be 0, as it is similar to the cubic graph.

Bibliography:

Websites:

http://en.wikibooks.org/wiki/Theory_of_Equations

(Date accessed – 11/05/09)

http://id.mind.net/~zona/mmts/intersections/intersectionLineAndParabolla1/intersectionLineParabolla1.html

(Date accessed – 09/05/09)

http://www.analyzemath.com/Calculators/Parabola_Line.html

(Date accessed – 13/05/09)

http://www.mathforum.org/library/drmath/view/65384.html

(Date accessed – 14/05/09)

http://en.wikipedia.org/wiki/Quadratic_equations

(Date accessed – 10/05/09)

http://www.math.vanderbilt.edu/~schectex/courses/cubic/

(Date accessed – 16/05/09)

http://en.wikipedia.org/wiki/Cubic_equation

(Date accessed – 17/05/09)

IGCSE Mathematics Second Edition – By Ric Pimentel and Terry Wall.

IBID Mathematics Higher Level (Core) – By Nigel Buckle and Iain Dunbar

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