<u>Answer:</u>
Using the pair of points (1, 1) and (0, 0) we have calculated the slope of the line
<u>Solution:</u>
Given that, we can use any two points from cartesian plane,
Let the two points be (0, 0) and (1, 1)
We have to find the slope of the line that, passes through the chosen two points.
Now, we know that, slope of a line that passes through
is given by:


Substitute these values in "m" formula,

Hence, the slope of the line that passes through (1, 1) and (0, 0) is 1.
The whole picture is not token correctly
Explanation:
a)


b) First, we have that

On the other hand,

Therefore, both expressions are equal. This makes sense, because selecting k elements from a group of n is the same than specify which elements you will not select. In order to specify those elements you need to select the n-k elements that will not be selected. Hence, each time you are selecting k from n, you are also selecting n-k from n, and from that reason both combinatorial numbers are equal.