Question 58455:  Here is a function that I have been dealing with at work: 
  
Y(x) = –3.3x2 + 0.5x + 300.
 
I need to use this function to tell researchers what value of x produces the maximum output signal for an MRI machine, Y.  Also, since everyone’s MRI machine is not exactly the same as mine, I want to give them a range of x values that will produce nearly the maximum output Y.  So, here are the questions: 
 
 
1.   What is the x value when Y is at its maximum value?
 
2.   What is the maximum value of Y?
 
3.   Since negative Y values are impossible for operating the MRI machine, what is the range of x values for Y to be greater than or equal to zero?
 
4.     What is the range of x values where Y is at 90% of its maximum value?
 
5.     Plot Graph showing all of the above information.
 
 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! Y(x) = –3.3x2 + 0.5x + 300.  
I need to use this function to tell researchers what value of x produces the maximum output signal for an MRI machine, Y. Also, since everyone’s MRI machine is not exactly the same as mine, I want to give them a range of x values that will produce nearly the maximum output Y. So, here are the questions:
 
1. What is the x value when Y is at its maximum value?  
x=-b/2a = -0.5/-6.6=0.0757575... 
2. What is the maximum value of Y? 300.02 
3. Since negative Y values are impossible for operating the MRI machine, what is the range of x values for Y to be greater than or equal to zero? 
-9.459169<=x<=9.61068  
4. What is the range of x values where Y is at 90% of its maximum value? 
0.9*300.02=279.018; -2.43424<=x<=2.5842  
5. Plot Graph showing all of the above information.  
  
Cheers, 
Stan H.
 
 
 
 
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