A car traveled at a steady speed for 120k. Due to mechanical problems, it returned at half that speed. If the total time for the round trip was 4hr 30 min, find the two speeds.
ive done this problem a few times and i cant find out how to do it. can someone please help me by doing it in and system of equations method to solving problems.
2007-01-11 12:48:08 · 4 answers · asked by Anonymous in Education & Reference ➔ Homework Help
since the second trip took twice the first trip, then the first trip probably took 1hr 30 min, and the second trip took 3hrs
the distance is 120 kilometers, and travelling 80 km/hr for 1 hr and 30 mins is 120 km
the second trip is also 120 kilometers, and travelling 40 km/hr for 3 hours is 120 km
the speed of the first trip is 80 km/hr for 1 hr and 30 mins
the speed of the second trip is 40 km/hr for 3 hours
total of 4 hrs and 30 mins
2007-01-11 13:03:51 · answer #1 · answered by dendroidsoldier15 2 · 0⤊ 0⤋
i'm going to objective to describe the main suitable i will: at first, whenever you desire to clean up for a variable (for this reason x), you are able to desire to placed the variable on one element and the different numbers on the different. So first placed the x on the left element of the equation. to do this, you would be conscious that x is adverse (-x). as a results of this, to stability the equation, you upload valuable x to the two factors: 5 + x = 8 - x + x Now, you recognize that -x + x equals 0, so which you would be able to now take that out of the equation: 5 + x = 8 Now you are able to desire to placed the 5 on the spectacular element so x could nicely be on my own. you recognize that 5 is a favorable quantity (+5), with the objective to stability the equation, you subtract 5 on the two factors: 5 - 5 + x = 8 - 5 5 - 5 equals 0, so which you would be able to now take that out of the equation: x = 8 - 5 you are able to now clean up x unquestionably. x = 3 So this implies the purely suitable answer is x = 3 If we plug in 3 to the equation, we are going to se that it is real. 5 = 8 - 3 5 = 5 i'm hoping this facilitates =)
2016-12-13 03:18:56 · answer #2 · answered by ? 3 · 0⤊ 0⤋
x = amount of time traveled = first leg
2x return trip as car went half as fast
x +2x = 4.5 hours
3x = 4.5
x = 1.5 hours for first leg
120k / 1.5 hours = 80 kph
120k / 3 hours return trip = 40 kph
woohoo !
2007-01-11 12:59:35 · answer #3 · answered by tomkat1528 5 · 0⤊ 0⤋
I think Tomkat is wrong. It should be X + X/2 not X + 2X
2007-01-11 13:07:43 · answer #4 · answered by Jakarta Worker 6 · 0⤊ 0⤋