Rogerio drives 1 hour and 18 min to meet a friend. the first 30 min of his trip was mostly highway driving, so he averaged 64 miles per hour for this portion. for the last 48 min of this trip, he averaged 50 miles per hour. what was his average speed for the entire trip?

a) 60 miles per hour
b) 58 miles per hour
c) 55 miles per hour
d) 53 miles per hour

C) 55 miles per hour

Step-by-step explanation:

In order to calculate this you just have to see how many miles did he traveled and then divided that by the minutes that he spent.

So in the first part of the trip he traveled 30 minutes at a speed of 64 miles, that makes up for 32 miles.

And in the second part of the trip he traveled for 48 minutes at 50 miles per hour, that makes for 40 miles

So he traveled 72 miles total, divided by 78 minutes=.923 miles per minute, we just multiply this by 60 and we have that he traveled at 55.38 miles per hour.

the balance is found at the link

step-by-step explanation:

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15