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Answer: 3 mi/h
Step-by-step explanation:
Here we have to find the speed at which Sarah walks to school, knowing the distance
she has walked and the time
she expends.
So, in this case we can use the following equation:
Where:
Solving:
This is Sarah's speed
The revenue function is a quadratic equation and the graph of the function
has the shape of a parabola that is concave downwards.
The correct responses are;
- (a) <u>R = -x² + 82·x</u>
- (b) <u>$1,645</u>
- (c) The graph of <em>R</em> has a maximum because the <u>leading coefficient </u>of the quadratic function for <em>R</em> is negative.
- (d) <u>R = -1·(x - 41)² + 1,681</u>
- (e) <u>41</u>
- (f) <u>$1,681</u>
Reasons:
The given function that gives the weekly revenue is; R = x·(82 - x)
Where;
R = The revenue in dollars
x = The number of lunches
(a) The revenue can be written in the form R = a·x² + b·x + c by expansion of the given function as follows;
R = x·(82 - x) = 82·x - x²
Which gives;
- <u>R = -x² + 82·x </u>
<em>Where, the constant term, c = 0</em>
(b) When 35 launches are sold, we have;
x = 35
Which by plugging in the value of x = 35, gives;
R = 35 × (82 - 35) = 1,645
- The revenue when 35 lunches are sold, <em>R</em> = <u>$1,645</u>
(c) The given function for <em>R</em> is R = x·(82 - x) = -x² + 82·x
Given that the leading coefficient is negative, the shape of graph of the
function <em>R</em> is concave downward, and therefore, the graph has only a
maximum point.
(d) The form a·(x - h)² + k is the vertex form of quadratic equation, where;
(h, k) = The vertex of the equation
a = The leading coefficient
The function, R = x·(82 - x), can be expressed in the form a·(x - h)² + k, as follows;
R = x·(82 - x) = -x² + 82·x
At the vertex, of the equation; f(x) = a·x² + b·x + c, we have;
Therefore, for the revenue function, the x-value of the vertex, is;
The revenue at the vertex is; = 41×(82 - 41) = 1,681
Which gives;
(h, k) = (41, 1,681)
a = -1 (The coefficient of x² in -x² + 82·x)
- The revenue equation in the form, a·(x - h)² + k is; <u>R = -1·(x - 41)² + 1,681</u>
(e) The number of lunches that must be sold to achieve the maximum revenue is given by the x-value at the vertex, which is; x = 41
Therefore;
- The number of lunches that must be sold for the maximum revenue to be achieved is<u> 41 lunches</u>
(f) The maximum revenue is given by the revenue at the vertex point where x = 41, which is; R = $1,681
- <u>The maximum revenue of the company is $1,681</u>
Learn more about the quadratic function here: