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Passes through (-5, 0), (1,0), and (-3, -16)

Is even and has a range of y < 2

Passes through (0, 0), (2, 2), and (4, 0)

 May 7, 2016
 #1
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A general quadratic function can be written as  y = a*x^2 + b*x + c,  where a, b and c are constants to be found.

 

For "Passes through (-5, 0), (1,0), and (-3, -16)" :

 

(-5,0)      0 = 25a - 5b + c

(1,0)       0 = a + b + c

(-3,-16)   -16 = 9a - 3b + c

 

You now have 3 equations in the 3 unknowns so you should be able to solve for a, b and c (you should get a=2, b=8 and c=-10)

 

 

For "Is even and has a range of y<= 2":

 

Note that y(-x) = y(x)  which means b = 0.

The maximum value of y is obtained when 2*a*x + b = 0 or x = 0 (can't have a = 0 or it wouldn't be quadratic).

So must have c = 2.     y = a*x^2 + 2.   For y to have a maximum value of 2, a must be negative.  

 

For "Passes through (0, 0), (2, 2), and (4, 0)"  use the same method as the first above.

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 May 8, 2016

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