+0

What are the vertex and the axis of symmetry of the equation?

-2
424
5
+2448

Have no idea how to solve this

Feb 20, 2018

#1
+956
+2

Tell me if you need an explanation.

Feb 20, 2018
#2
+2448
+1

I need an explanation

RainbowPanda  Feb 20, 2018
#3
+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
+111329
+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

Feb 20, 2018
#5
+2448
+1

Wow tysm! This really helped ^-^

RainbowPanda  Feb 20, 2018