Consider the following sequence of figures.

Question

Consider the following sequence of figures.
Figure 1 contains 5 line segments.
Figure 2 contains 9 and figure three contains 13.
Given that figure n contains 801 line segments, show that n=200. already did this first part. I need to figure out how to do the part below
Find the total number of line segments in the first 200 figures.

Answer 1

The sequence is: 5, 9, 13, 17, ...

The common difference is 4

S_n = (n/2)(2a₁ + (n - 1)d)

S₂₀₀ = (200/2)(2(5) + 199(4))

 

Can you complete and answer?