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Quadratic Functions.............................

Evaluate given quadratic functions
 
(1)f(x)=x^2+8x+6, Find f(-5)
 
(2)g(x)=5x^2-4x+8, g(-9)
 
(3) f(x)=x^2+2x-17, f(a-4)
 
Find all fixed points for the following functions by setting the function equal to x and solving the resulting equation for x
 
(1) f(x)=x^2-5x+8
 
 
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1 Answer

1.   (-5)2 + 8(-5) + 6 = 25 - 40 + 6 = -9
 
2.  5(-9)2 - 4(-9) + 8 = 5(81) + 36 + 8 = 405 + 36 + 8 = 449
 
3.  (a-4)2 + 2(a-4) - 17   =   a2 - 8a + 16 + 2a - 8 - 17 = a2 - 6a - 9 = (a-3)2
 
 
 
Going by the directions on that last one...
x = x2 - 5x + 8
 
0 = x2 - 6x + 8
 
0 = (x-4)(x-2)
 
x={2, 4}