SOLUTION: For the first 4 km of a 10km journey, Jerry and Jerome travelled together at an average speed of x km/h. For the next 6 km, Jerry increased his average speed by 2 km/h while Jerome
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Question 875145: For the first 4 km of a 10km journey, Jerry and Jerome travelled together at an average speed of x km/h. For the next 6 km, Jerry increased his average speed by 2 km/h while Jerome decreased his average speed by 1 km/h.
If the difference in the total time taken to complete the entire journey by Jerry and Jerome is 1.5 hours, find the value of x.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
For the first 4 km of a 10km journey, Jerry and Jerome travelled together at an average speed of x km/h. For the next 6 km, Jerry increased his average speed by 2 km/h while Jerome decreased his average speed by 1 km/h.
If the difference in the total time taken to complete the entire journey by Jerry and Jerome is 1.5 hours, find the value of x.
***
travel time=distance/speed
-6x+6+6x+12=1.5(x-1)(x+2)=1.5(x^2+x-2)
1.5(x^2+x-2)=18
1.5x^2+1.5x-3=18
1.5x^2+1.5x-21=0
x^2+x-14=0
solve for x by quadratic formula:
a=1, b=1, c=-14
ans:
x≈-4.27(reject)
or
x≈3.27
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