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Two points on a parabola are (-3,5) and (11,5). What is the equation of the axis of symmetry?

 May 30, 2019
 #1
avatar+103097 
+2

The axis of symmetry will  be found by adding the x coordinates of these points and dividing by 2......so

 

 

x  =  [ -3 + 11]  / 2

 

x  =  [ 8 ] / 2

 

x = 4   ⇒   axis of symmetry

 

 

cool cool cool

 May 30, 2019
 #3
avatar+25 
-5

why divide by 2?

ProffesorNobody  May 30, 2019
 #2
avatar+25 
-5

???? how does that work

 May 30, 2019
edited by ProffesorNobody  May 30, 2019
 #5
avatar+103097 
+1

This parabola opens upward

 

The axis of symmetry for a parabola that opens upward (or downward ) will  always  be the average of the two x values whenever those two x values are associated with the same y value 

 

 

Thus...to find the average....add the x values and divide by 2

 

 

cool cool cool

CPhill  May 30, 2019
 #6
avatar+25 
-5

average....?

ProffesorNobody  May 30, 2019
edited by ProffesorNobody  May 30, 2019
 #7
avatar+25 
-5

does it work for the y to?

ProffesorNobody  May 30, 2019
 #10
avatar+103097 
+2

Yes....if we had   (4, 9)  and (4, 11).....the axis of symmetry would be

 

y =  [ 9 + 11 ] / 2  =  20 / 2   =  10

 

cool cool cool

CPhill  May 30, 2019
 #11
avatar+25 
-5

ok what is that method called?

ProffesorNobody  May 30, 2019
 #12
avatar+103097 
+2

Not sure it has a name......

 

cool cool cool

CPhill  May 30, 2019
 #13
avatar+25 
-4

awwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww

ProffesorNobody  May 31, 2019
 #4
avatar+25 
-5

how do you get points: sorry off topic

 May 30, 2019
 #8
avatar+103097 
+1

I think that anyone who is a member can give you points....I just gave you a few!!!!

 

 

cool cool cool

CPhill  May 30, 2019
 #9
avatar+25 
-5

YAY THX

ProffesorNobody  May 30, 2019

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