Friday

December 19, 2014

December 19, 2014

Posted by **ty** on Thursday, December 15, 2011 at 3:05pm.

- algebra -
**Reiny**, Thursday, December 15, 2011 at 5:12pmfirst speed --- x

second speed --- x-1

time at first speed = 6/x

time at 2nd speed = 7/(x-1)

6/x + 7/(x-1) = 2 1/42 = 85/42

times: 42x(x-1)

6(42)(x-1) + 7(42)x = 85x(x-1)

252x - 252 + 294x = 85x^2 - 85x

85x^2 - 631x + 252 = 0

x = (631 ± √312481)/170

= 7 or ...

aha , it facored

(x-7)(85x - 36) = 0

x=7 or x = 36/85

but 36/85 would make his 2nd speed negative, not very likeyly, so

x = 7

for the first leg he ran at 7 mph, for the 2nd leg he ran at 6 mph

check: 6/7 + 7/6 = (36+49)/42 = 85/42 = 2 1/42

**Answer this Question**

**Related Questions**

PSAT - Math - Hello, I am reviewing my psat and looking at the questions I got ...

Algebra (check answers) - Could you please check my answers we are using ...

algebra - A jogger leaves home and runs at a constant speed of 4 miles per hour...

algebra - monique ran one mile in 6 minutes.her average speed was how many miles...

math - A marathon runner ran 26.2 miles in 2 h 30 min. Find these rates: a. ...

algebra - Rachel allows herself 1 hour to reach a sale appointment 50 mile s ...

math - on friday catlin ran 1 and 1/5 miles on sunday she ran 1 and2/5 miles.On ...

Math - A small truck is to be driven 300 miles on a freeway at a constant speed ...

maths - A motorist travels 120 miles to his destionation at an average speed of ...

math - Jan Maya and Sara ran a total of 64 miles. two ran the same and one ran 8...