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Whats the Domain and Range of this linear equation:

 

f(x)=x^2+4x-5

 Dec 14, 2020
 #1
avatar+117546 
+1

f(x)    =  1x^2  + 4x   - 5

 

The form is    f(x)  = ax^2 + bx + c

 

This is a polynomial.....a polynomial always has a domain of  all real numbers  (it is continuous  on the x axis )

 

This si a parabola that turns upward.....we  can find  the  x value that  gives a minimum  by

 

-b/ (2a)   = -4 / ( 2 (1)  =   -2

 

To find the  y value  for this x

 

1 (-2)^2  + 4(-2)  - 5  =   4 - 8  - 5   = -9

 

1 is the  minimum value in the range....and  there is no max  ( the function continues "upward" forever )

 

So....the range is  [ -9, infinity  )

 

 

cool cool cool

 Dec 14, 2020
edited by CPhill  Dec 14, 2020

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