Question

Joseph needs to drive 42 miles. They were going to drive at a certain average speed, but if they drive 10 mph faster, the trip will take 6 minutes (1/10 of an hour) less time. How fast were they going to drive? Write out the equation(s) ​

Answer 1

Answer:

The speed is 60 mph.

Step-by-step explanation:

distance = 42 miles

Let he drove with speed v and time is t.

distance = speed x time

42 = v t ..... (1)

42 = (v + 10)(t - 1/10) ..... (2)

$42 = 42 -\frac{v}{10}+ 10 t - 1\\\\t =\frac{10+v}{100}\\\\Put in (1)\\\\42 = \frac{v(10+v)}{100}\\\\v^2 + 10 v - 4200 = 0 \\\\v = \frac{-10\pm \sqrt{100+4\times 4200}}{2}\\\\v =\frac{- 10 \pm 130}{2}\\\\v =- 70 mph, 60mph$

So, the speed cannot be negative so the speed is 60 mph.