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1.Jeff the fly starts at the point (0,0) in the coordinate plane. At each step, Jeff takes a step to the right, left, up, or down. After 10 steps, how many different points could Jeff end up at?

 

2.Ten points are chosen on a circle. A line segment is drawn between every pair of chosen points. How many line segments are drawn?

 Feb 15, 2020
 #1
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1. Jeff the fly can reach 10^2 + 9^2 = 181 points.

 

2. There are 10 ways to choose the first point, then 9 ways to choose the second points, so there are 10*9 = 90 line segments.

 Feb 15, 2020
 #3
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Ah, that's 90 POINTS on a circle, a line segment is two points touching each other, which means it's 90/2 = 45

AnimalMaster  Feb 15, 2020
 #4
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1. Thanks, 181 is right!

Guest Feb 15, 2020
 #5
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On the link, it was 121. But okay.

AnimalMaster  Feb 16, 2020
 #2
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1. the answer that i agree with is here:

https://web2.0calc.com/questions/help-me-please_35236

 

2. \(\binom{10}{2} = 45\) line segments

 Feb 15, 2020

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