Answer:
A option
Step-by-step explanation:
The riddle answer is 24.
A riddle for the number 68 is: 12 more than 14 times 4
from x15 to x 25 is 4 - -16 = -20 degree change
25 -15 = 10000 feet
-20/10 = -2 degrees every 1000 feet
Answer:
a) Suppose that F is ordered in ascending order: 
. Then, the complement of F can be written as
which is the union of a finite number of open intervals, then 
is an open set. Thus, F is a closed subset of the real numbers.
b) Take an arbitrary element of F, let us say 
. Now, choose a real number 
such that
there are not other element of F, because is less that the minimum distance between and its neighbors.
In case that 
we only consider 
, and if 
we only consider 
.
Then, all points of F are isolated.
Step-by-step explanation:
If we have 2 coordinates say: (x1,y1) and (x2,y2)
Then the formula for the midpoint is:
((x1+x2)/2,(y1+y2)/2)
And the formula for the distance is:
Sqrt((x2-x1)^2+(y2-y1)^2)
So here we have (-1,-4) and (-7,4)
The midpoint is:
((-1+-7)/2,(-4+4)/2) = (-8/2,0/2) = (-4,0)
The distance is:
Sqrt((-7- -1)^2+(4- -4)^2)
= sqrt((-6^2)+(8^2))
=sqrt(36+64)
=sqrt(100)
=10
