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Question 38115: I need help with the following. I have been looking online, and in my Ti83 calculator instructions and can't find help. When I enter the y=x(300-3x) into the y= button on my Ti83 calculator nothing comes up on the graph. My teacher did not explain how to do this, what little she did explain... does not work.
This problem is suppose to be done with a graphing calculator.
* The combined area of two adjacent corrals bordering a river is given by y=X(300-3x). Where X is the length in feet of the sides that end in the river and Y represents the total area of the two corrals. (The 300 represents comes from the fact that there is only 300 feet of fence.) Use your calculator to sketch the graph of y=x(300-3x.
a). the ordered pair (40,7200) is on the graph. This means that when the length of one side of the corrals is 40 ft, the area is 7200 ft^2. Interpret what this ordered pair (80, 4800) represents in the context of this problem.
b). what is the area of these corrals if x=25? What are the dimensions of the corrals?
c). what values of x make sense in the context of this problem? HINT:lengths and areas can not be negative.
d). what x-value yields the maximun area? HINT:Find the maximun on the graph using your calculator. What would be the dimensions of the corrals?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! When I enter the y=x(300-3x) into the y= button on my Ti83 calculator nothing comes up on the graph. My teacher did not explain how to do this, what little she did explain... does not work.
You need to adjust the WINDOW so you can see the graph.
Make the following adjustments:
XMIN -10; XMAX 100; YMIN -3300; YMAX 10000
This problem is suppose to be done with a graphing calculator.
* The combined area of two adjacent corrals bordering a river is given by y=X(300-3x). Where X is the length in feet of the sides that end in the river and Y represents the total area of the two corrals. (The 300 represents comes from the fact that there is only 300 feet of fence.) Use your calculator to sketch the graph of y=x(300-3x.
a). the ordered pair (40,7200) is on the graph. This means that when the length of one side of the corrals is 40 ft, the area is 7200 ft^2. Interpret what this ordered pair (80, 4800) represents in the context of this problem.
AREA= 80*4800=384000 sq. ft.
b). what is the area of these corrals if x=25? What are the dimensions of the corrals?
Hit the buttons "2nd" TABLE and scroll til X=25. The corresponding Y value
is the other dimension. I get 5625
c). what values of x make sense in the context of this problem? HINT:lengths and areas can not be negative.
To keep x(300-3x)>0 you need 0
d). what x-value yields the maximun area? HINT:Find the maximun on the graph using your calculator. What would be the dimensions of the corrals?
Hit the buttons "2nd" CALC Maximum or Use TRACE to move the cursonr up to
the topmost point of the graph.
I get x=50, y=75
Cheers,
Stan H.
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