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A man writes 1 on the first line of his paper, then writes 2 and 3 on the second line, then 4, 5, and 6 on the third, and continues so that on any line n he writes the first n integers following the last integer on line n - 1. What is the sum of the first and last integers on line 17

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Answer: 290

Step-by-step explanation:

[tex]First\ integer\ on\ line\ n\ is:\ \dfrac{n^2}{2}-\dfrac{n}{2}+1 \\\\For \ line\ 17\ : \dfrac{17^2}{2}-\dfrac{17}{2}+1 =137\\\\\\Last \ integer\ on\ line\ n\ is:\ \dfrac{n*(n+1)}{2} \\\\For\ line\ 17:\ \dfrac{17*(17+1)}{2} =153\\\\Sum=137+153=290[/tex]

I have not say the equation in u(n+3) for the recurrence,

the resolution of the equation caracteristic and the resolution of a system of 3 equations with 3 variables.

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