SOLUTION: Happy Tuesday everyone! I am looking for some expertise when it comes to solving "story" or "word" problems dealing with quadratic equations. My teacher requires that when we work

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Question 362033: Happy Tuesday everyone! I am looking for some expertise when it comes to solving "story" or "word" problems dealing with quadratic equations. My teacher requires that when we work through a problem that we show her all of the steps to show what we did to get our answer. I was wondering if you could help me?
11.5, #10
Directions: Solve
10.) The daily number of request, f(x), for a song that a local radio station receives can be modeled by f(x)=x^2-5x+11 (it should read x squared)
where x is the number of days after the song has been released. During which time period will the daily number of requests be below 7?
The book shows the answer to be: between day 1 and 4. But, I have not a clue what steps I need to perform to get this as my final outcome. Thanks so much!
Found 2 solutions by ewatrrr, solver91311:
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!


Hi, 

requests to be played after release time x model: 

f(x)=x^2-5x+11

7 = x^2 - 5x + 11

-4 = x^2 - 5x 

x = 1 or x = 4  graph indicates that as well 

graph will be below the '7 line' when x is between 1 and 4

 

Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!
 





The graph of your function is a parabola opening upward.  What you want are the x-coordinates of the two intersecting points between your parabola and the horizontal line .  All you need to do is set your function equal to 7 and then solve the resulting quadratic equation.

















Solve for . Hint: It factors.





John



My calculator said it, I believe it, that settles it


The Out Campaign: Scarlet Letter of Atheism


 

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