You calculate the number of ways that 2 people can be chosen from 10.
The formula:
n! / r! * (n-r)! =
10! / 2! * 8! =
10 * 9 * 8! / 2 * 8! =
10 * 9 / 2 =
45 handshakes
Source:
http://www.1728.org/combinat.htm
In my case, I got nine months. Where both y values would equal 270.
Answer:
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Step-by-step explanation:
Here's an example...
So, in our last example...
In the point ( -2, -1 ), x1 = -2 and y1 = -1 ... and, in the point ( 4, 3 ), x2 = 3 and y2 = 3
m = ( y2 - y1 ) / ( x2 - x1 ) = ( 3 - ( -1 ) ) / ( 4 - ( -2 ) ) = 4 / 6 = 2 / 3
But, notice something cool...
The order of the points doesn't matter! Let's switch them and see what we get:
In the point ( 4, 3 ), x1 = 4 and y1 = 3 ... and, in the point ( -2, -1 ), x2 = -2 and y2 = -1
m = ( y2 - y1 ) / ( x2 - x1 ) = ( -1 - 3 ) / ( -2 - 4 ) = -4 / -6 = 2 / 3 ... Same thing!
Let's try our new formula with the second example in the last lesson:
It was a line passing through
( -1, 4 ) and ( 2, -2 )
m = ( y2 - y1 ) / ( x2 - x1 ) = ( -2 - 4 ) / ( 2 - ( -1 ) ) = -6 / 3 = -2