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write y=x^2-2x-8 in intercept form. then find the x-intercept and the vertex

Guest Apr 3, 2017
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 #1
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+2

 

 

It's easier to find the x intercepts by factoring x^2 - 2x - 8   and setting  y = 0

 

0 = ( x - 4) (x + 2)

 

And setting both of the factors to 0 and solving for x, we have that x = 4  and x = -2

 

To find the vertex :

 

 y=x^2-2x-8   complete the square on x

 

y = x^2 - 2x + 1 - 8 - 1      factor the first three terms

 

y = (x - 1)^2  - 9

 

And the vertex  is  ( 1, - 9)

 

Here's the graph : https://www.desmos.com/calculator/pqqn4ceovc

 

 

cool cool cool

CPhill  Apr 3, 2017
edited by CPhill  Apr 3, 2017
 #2
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+1

thx for the help ^-^

Guest Apr 3, 2017

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