Help with part b pls thank u
2 answers:
Answer:
Step-by-step explanation:
- speed = distance / time
- time = distance / speed
a)
i)
<u>Time taken at the first part:</u>
ii)
<u>Time taken at the second part:</u>
- (190 - 105) / (x + 12) =
- 85/(x + 12)
b)
<u>If time is 3 hours and 15 minutes = 3 1/4 hours = 13/4 hours, the equation is:</u>
- 105/x + 85/(x + 12) = 13/4
- 4(x + 12)*105 + 4(85x) = 13x(x + 12)
- 13x² - 604x - 5040 = 0
c)
<u>Solve the equation:</u>
- 13x² - 604x - 5040 = 0
- x = [604 ± √((-604)² + 4*13*5040) ]/26 =
- [604 ± √626896]/26 =
- [604 ± 791.77]/26
- x = (604 + 791.77)/26 = 53.68 km/h (taking positive root only)
d)
- 105/x = 105/53.68 h = 1.956 h = 1 h 0.956*60 min = 1 h 57 min (rounded)
- 85/(53.68 + 12) = 85/65.68 = 1.294 h = 1 h 0.294*60 min = 1 h 18 min (rounded)
Answer:
see below
Step-by-step explanation:
Let t = time (in hours)
a) i) <u>First 105 km of journey</u>
ii) <u>Rest of journey</u>
distance = 190 - 105 = 85 km
speed = km/h
b) 3 hours 15 minutes = 3.25 hours
total time =
multiply by 4:
c)
(to 2 decimal places)
d) time ≥ 0, therefore, x = 53.68 only
Substitute x = 53.68 into the expression for and solve for :
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