Question 672211
 if A walked 1km/hr faster then A would have taken 10 min less to walk 2km/hr. find the speed of A
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let s = the speed of A
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Change 10 min to 10/60 = 1/6 hr
:
slow time - fast time = 10 min
{{{2/s}}} - {{{2/((s+1))}}} = {{{1/6}}}
:
mult by 6s(s+1), cancel the denominators and you have:
6(s+1)*2 - 6s(2) = s(s+1)
12(s+1) - 12s = s^2 + s
12s + 12 - 12s = s^2 + s
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A quadratic equation
s^2 + s - 12 = 0
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Factors to
(s+4)(s-3) = 0
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the positive solution is what we want here
s = 3 km/h is his speed
:
:
Check this
2/3  - 2/4 =
8/12  - 6/12 = 2/12 = 1/6