Question 64359:  Can you help me solve this application?  
 
A particle moves along a straight line according to the formula s=2t^2+t-6, where s represents the distance in inches from the beginning point, and t represents the time in seconds.  Find the time (to the nearest hundredth of a second when the particle is 5 incesh from the beginning point.
 
Thanks 
Elizabeth 
 Answer by Edwin McCravy(20064)      (Show Source): 
You can  put this solution on YOUR website! Can you help me solve this application? 
A particle moves along a straight line 
according to the formula s=2t² + t - 6, where 
s represents the distance in inches from the 
beginning point, and t represents the time 
in seconds. Find the time (to the nearest 
hundredth of a second when the particle is 
5 inches from the beginning point. 
Thanks
Elizabeth
s = 2t² + t - 6
Just substitute 5 for s and solve for t:
5 = 2t² + t - 6
0 = 2t² + t - 11
That won't factor:
      2t² + t - 11 = 0
So we use the quadratic formula:
                  ______ 
            -b ± Öb²-4ac
        x = —————————————
                2a 
where a = 2; b = 1; c = -11; x = t
                     ______________ 
             -(1) ± Ö(1)²-4(2)(-11)
        t = ————————————————————————
                     2(2) 
                   _____ 
             -1 ± Ö1+88
        t = —————————————
                 4
                   __ 
             -1 ± Ö89
        t = ——————————
                 4
                      
Using the +, we get t about 2.108495283 seconds, 
or about 2.11 seconds, to the nearest hundredth
of a second.
                      
Using the -, we get a negative value, which we discard.
Edwin 
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