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Answer:
y = 2x³ +x² -3x +6
Step-by-step explanation:
The polynomial correlation function of a graphing calculator can work with the table of function values to give you the equation. (See attached)
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If you want to solve this by hand, you can write the equations for the unknown coefficients in the polynomial function, then solve those. First of all, notice that you are given the y-intercept, (0, 6), so you know one of the coefficients already. That leaves a system of 3 equations in 3 unknowns that need to be solved.
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<em>Writing the equations</em>
... ax³ +bx² +cx +6 = y . . . . the generic linear equation in a, b, c that you're writing
For x = -1:
... -a +b -c +6 = 8
For x = 1
... a + b + c + 6 = 6
For x = 2
... 8a +4b +2c +6 = 20
In augmented matrix terms, this set of linear equations looks like ...
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<em>Solving the equations</em>
There are a number of ways to solve these. Again, a graphing calculator often has solution functions, such as reducing a matrix to row-echelon form, that will solve this in a keystroke or two.
If you add the first two equations, you get ...
... 2b = 2 ⇒ b = 1
Substituting that into the first equation allows you to simplify it to ...
... -a -c = 1
Dividing the third equation by 2 (and substituting for b) makes it ...
... 4a +c = 5
Adding these equations gives ...
... 3a = 6 ⇒ a = 2
Then ...
... c = -a -1 = -2 -1 = -3
And our polynomial function is ...
... y = 2x³ +x² -3x +6
Answer:
9) y = -200x + 1200
11) slope = -2
15) $2,450
16) 9 days
Step-by-step explanation:
9) Given the two points from the graph:
Let (x₁, y₁) = (0, 1200)
(x₂, y₂) = (1, 1000)
Substitute these values into the following slope formula:
m = (y₂ - y₁)/(x₂ - x₁)
m = (1000 - 1200)/(1 - 0)
m = -200/1
m = -200
The slope of the line is -200.
Next, we need to determine the y-intercept, which is the point on the graph where it crosses the y-axis. Upon observing the graph, it shows that the line crosses at point (0, 1200). The y-coordinate of this ordered pair is the value of the y-intercept, b = 1200.
Therefore, the linear equation in slope-intercept form is y = -200x + 1200.
<h3>11) Given the points, (5, -18) and (-4, 0): </h3>Let (x₁, y₁) =(5, -18)
(x₂, y₂) = (-4, 0)
Substitute these values into the following <u>slope formula</u>:
m = (y₂ - y₁)/(x₂ - x₁)
Therefore, the slope of the line is -2.
<h3>15) Solve:</h3>Given the fixed fee of $200, and the $150 per hour after the initial meeting:
We can represent these in slope-intercept form:
y = 150x + 200
y = total cost for the Attorney's services
x = number of hours worked.
The y-intercept in this given problem is $200, which represents the flat fee charged for the initial meeting. While the slope in this equation is $150, which is the hourly rate that an Attorney charges his clients after the initial meeting.
If an Attorney works for 15 hours, then:
Let x = 15, and substitute its value into the equation to find the total cost:
y = 150x + 200
y = 150(15) + 200
y = 2,250 + 200
y = 2,450
Therefore, a client will pay a total of $2,450 for an Attorney's 15 hours of work.
<h3>16) Solve: </h3>Given the water level on a Lake of 165 inches after a rainstorm, and the water level's receding rate of 3 inches per day:
We can establish the following linear equation to model this given problem:
L = -3d + 165
Where:
L = represents the water level of the Lake
d = number of days that the water level recedes
In order to find the number of days it will take before the water level recedes to 84 inches:
Substitute the value of L = 84 into the equation:
L = -3d + 165
84 = -3d + 165
Subtract 165 from both sides:
84 - 165 = 3d + 165 - 165
-27 = -3d
Divide both sides by -3:
9 = d
Therefore, it will take 9 days for the water level to be at 84 inches.