You can put this solution on YOUR website! After completing a trip of 126 km, Victor finds that he can save 1 hour if he increases his speed by 8 km/hr.
What is his original speed?
:
Let s = his original speed
then
(s+8) = his faster speed
;
Write a time equation:
;
Original time = faster time + 1 hr = + 1
:
Multiply by s(s+8)
s(s+8)* = s(s+8)* + s(s+8)(1)
:
cancel the denominators, resulting in
126(s+8) = 126s + s(s+8)
126s + 1008 = 126s + s^2 + 8s
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A quadratic equation
s^2 + 8s - 1008 = 0
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You can us the quadratic formula, to find s, but this will factor to
(s-28)(s+36) = 0
The positive solution
s = 28 mph is his original speed
:
:
See if that works out, find the time of each trip:
126/28 = 4.5 hrs
126/36 = 3.5 hrs, an hour less at the faster speed
