Anna drives 45 km to work each day. One day she drives the first 25 km at an average speed of 82 km/h. She takes 36 minutes to drive the remaining distance.
Calculate her average speed, in km/h, for the whole journey.

Anna drove at an average speed of 49.73 km/h

Step-by-step explanation:

Average Speed

If an object moves at different speeds to cover a certain total distance dt in a total time tt, the average speed is:

Anna drives a total distance of dt=45 km each day. One day she drives a distance of d1=25 km at v1=82 Km/h. The time taken for that distance is:

She takes t2=36 minutes to drive the remaining distance. 36 minutes is 36/60=0.6 h, thus the total time is:

The average speed is:

Anna drove at an average speed of 49.73 km/h

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation: