2 answers:
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Answer:
O 81 km per hour
Explanation
Given parameters:
Number of days traveled = 3 days
Distance covered on the first day = 1080km
Time of travel = 10hrs
Rate of travel = 108km/hr
Time of travel on second day = 12hrs
Rate of travel = 90km/hr
Time of travel on third day = 18hrs
Rate of travel = 60km/hr
Unknown
Average speed = ?
To find the average speed, we sum the distances and divide by the sum of the time.
Average speed =
we do not know the second and third distances;
Distance = speed x time
D2 = 90 x 12 = 1080km
D3 = 60 x 18 = 1080km
Now;
Average speed =
Average speed = = 81km/hr
The average speed is 81km/hr
has critical points wherever the partial derivatives vanish:
Then
- If
, then
; critical point at (0, 0)
- If
, then
; critical point at (1, 1)
- If
, then
; critical point at (-1, -1)
has Hessian matrix
with determinant
- At (0, 0), the Hessian determinant is -16, which indicates a saddle point.
- At (1, 1), the determinant is 128, and
, which indicates a local minimum.
- At (-1, -1), the determinant is again 128, and
, which indicates another local minimum.