You can put this solution on YOUR website! A car travels 100 miles at a certain speed.
If the speed was 5 miles faster the trip would take an hour less.
Find the speed.
:
let s = actual speed
then
(s+5) = faster speed
:
Write a time equation time = dist/speed
actual time - faster time = 1 hr - = 1
multiply by s(s+5), cancel the denominators
100(s+5) - 100s = s(s+5)
100s + 500 - 100s = s^2 + 5s
A quadratic equation
0 = s^2 - 5s - 500
Factors to
(s+25)(s-20) = 0
the positive solution
s = 20 mph is the actual speed
:
:
Check this by finding the actual speeds
100/20 = 5 hrs
100/25 = 4 hrs
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time diff: 1 hr
