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# Help. ​

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Help.

NotSoSmart  Nov 1, 2017
Sort:

#1
+82752
+1

Look at this, NSS

In the form

ax^2  +  bx  + c

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

So we have

-2x^2  + 8x  - 18

So......b = 8   and   a  = -2

So.......the x coordinate of the vertex  is   [ -8 ] / [ 2 * -2 ]  =  -8/-4  =  2

And the axis of symmetry has the same value  ⇒     x  =  2

We could find the y value of the function by  putting 2 back into it, but we don't have to in this case

The first answer is the only one that makes sense

CPhill  Nov 1, 2017
#2
+82752
+1

For the second one.....the vertex  is  (10, 60)

The seconds are on the x axis and the speed is on the y axis.....so.......

It takes 10 seconds for the car to reach 60 mph

CPhill  Nov 1, 2017

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