Take n more points on a line segment. How many lines are there?

N points on the line segment,

Taking the first point as the left end point can form n- 1 line segments. Note that it is n- 1! Not n+ 1!

Taking the second point as the left end point, n-2 line segments can be formed.

…………

With the n- 1 point as the left end point, 1 line segment can be formed.

Taking the nth point as the left end point can form 0 line segments.

therefore

The number of bus segments is: (n- 1)+(n-2)+…+ 1.

=n(n- 1)/2

That is, a method for calculating line segments: number of points * (number of points-1)/2.

I am an Olympic math teacher, and my answer is definitely right! If you don't believe me, verify it yourself!

A line segment, do you think there are 2 points or 0 points on the line segment? According to your logic, there are 0 points on a line segment! ! ! Joke!