Question 67147: Hi,
I seem to be having problems plotting a quadratic graph.
I have the following formula
pi r^2 + 180r - 6000 = 0
My two values for r are r(x) = 29 or r(x) = -64
However, when creating a table to create the graph, I am getting very strange values to plot the Y axis with. Such as:
r(x) = -64 so y = -30388 while r(x) = 29 y = 1862
Which in turn does not give the desirable "U" shape quadratics graph but more like a linear straight line graph.
Any help would be much appreciated
Thanks
Shaun Halliday
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! I seem to be having problems plotting a quadratic graph.
I have the following formula
pi r^2 + 180r - 6000 = 0
My two values for r are r(x) = 29 or r(x) = -64
However, when creating a table to create the graph, I am getting very strange values to plot the Y axis with. Such as:
r(x) = -64 so y = -30388 while r(x) = 29 y = 1862
Which in turn does not give the desirable "U" shape quadratics graph but more like a linear straight line graph.
:
I put y = 3.14x^2 + 180x - 6000 into the graphing feature on this website, using a scale of x:-100,=50 and y:+/-10000. I got:
:
For x = 29, I got your value of 1862, but for x = -64, I got -4652
:
Here is a table for some values for x, including the two that you mentioned,
x | y
---------
-90 | +3246
-64 | -4652
-50 | -7146
-30 | -8573
-10 | -7486
0 | -6000
+20 | -1143
+29 | +1862
+40 | +6227
:
Plotting these should look just like the graph above
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