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# Use the vertex form to write the equation of the parabola.

-2
362
2
+2448

Feb 20, 2018

#1
+18057
+2

First find the vertex.....can you tell me what that is?

From the graph the vertex is   h,k (or the x,y point) =  -3,4

y = a(x-h)^2 +k   is vertex form      Now let's put  -3 , 4 in there

y= a (x-(-3))^2 + 4       Now how can we find the value of 'a' ?  find a convenient point on the graph (not the vertex)     ....look at x = -5       at that point y = -4    Sub this in to the working equation then solve for 'a'

-4 = a (-5 +3)^2 +4        means 'a' = -2   soooooo the equation becomes

y = -2(x+3)^2 +4

Feb 20, 2018

#1
+18057
+2

First find the vertex.....can you tell me what that is?

From the graph the vertex is   h,k (or the x,y point) =  -3,4

y = a(x-h)^2 +k   is vertex form      Now let's put  -3 , 4 in there

y= a (x-(-3))^2 + 4       Now how can we find the value of 'a' ?  find a convenient point on the graph (not the vertex)     ....look at x = -5       at that point y = -4    Sub this in to the working equation then solve for 'a'

-4 = a (-5 +3)^2 +4        means 'a' = -2   soooooo the equation becomes

y = -2(x+3)^2 +4

ElectricPavlov Feb 20, 2018
#2
+2448
+1

Tysm ^-^

RainbowPanda  Feb 20, 2018