Question

...

Answer 1

Do you know the formula for the vertex (peak) of a parabola?
if
y= a x^2 +b x +c
where is the vertex?

Answer 2

Look at this
http://hotmath.com/hotmath_help/topics/vertex-of-a-parabola.html

Answer 3

yea I know that

Answer 4

What do you know?
what is the formula for the x value of the vertex for
y= a x^2 +b x +c

Answer 5

The site tells you, if you read the section below the figure.

Answer 6

in the standard form, y = ax2 + bx + c, the expression

\[ x= -\frac{b}{2a} \]

gives the x-coordinate of the vertex.

Answer 7

ok..

Answer 8

For your problem, can you match up your equation to find a and b?

Answer 9

y = –0.000475x^2 + 0.851x
y = a x^2 + b x + c

Answer 10

what now?

Answer 11

what is a and b for your problem?

Answer 12

Here is what we are doing.

We are given an equation (a parabola), and we want to find where it peaks.
To find where it peaks, (the x value) and how high (the y value) we use a formula (that we memorized). The formula for where it peaks is
x= -b/2a

what is b and what is a? we need those to use the formula.

To find b and a we look at our equation
y = –0.000475x^2 + 0.851x

and match it to the equation
y= a x^2 +b x +c

a is the number in front of the x^2 and b is the number in front of the x

once you get a and b , you use those numbers in
x= -b/2a to find x
can you find a and b?