+0  
 
-2
184
5
avatar+2077 

Have no idea how to solve this

RainbowPanda  Feb 20, 2018
 #1
avatar+956 
+2

Tell me if you need an explanation. 

Julius  Feb 20, 2018
 #2
avatar+2077 
+1

I need an explanation

RainbowPanda  Feb 20, 2018
 #3
avatar+956 
+3

KK: 

To find the axis of symmetry you use the formula: x= -b/2a 

Once you find the axis of symmetry you can plug into the original formula to find the y value. Since the axis of symmetry is the x value of the vertex. 

Julius  Feb 20, 2018
 #4
avatar+91149 
+3

In the form

 

y  =  ax^2  + bx + c

 

The x coordinate of the vertex  is  given  by      -b / [2a]

 

So....we have

 

y  = -2x^2 + 28x  -  18       ......    b  = 28     a   =  -2

 

So...the x coordinate of the vertex  is given by

 

-(28) / [ 2 * -2]   =   -28 / -4   =  7

 

So  to find the y coordinate of the vertex...sub this value back into the function

 

-2(7)^2  + 28(7)  -  18   =

-98 +  196 - 18  =

80

 

So....the vertex  is  ( 7, 80)

 

This is a  vertical parabola    ....the  axis  of symmetry  is just   

 

x    =  the x coordinate of the vertex

 

x  =  7 

 

Here's the graph :  https://www.desmos.com/calculator/wcucis6wzt

 

 

cool cool cool

CPhill  Feb 20, 2018
 #5
avatar+2077 
+1

Wow tysm! This really helped ^-^

RainbowPanda  Feb 20, 2018

5 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.