Question 1197683
Given a1=3, and a5=-17 (the first and the fifth number in an arithmetic series) what's a20 (the twentieth term in the series)
<pre>Common difference, or {{{matrix(1,3, d, "=", (matrix(1,11, Value, of, larger, term, number, "-", Value, of, smaller, term, number))/(matrix(1,7, Larger, term, number, "-", Smaller, term, number)))}}}
                        {{{matrix(4,2, "=", (a[5] - a[1])/(5 - 1), "=", (- 17 - 3)/(5 - 1), "=", (- 20)/4,
"=", - 5)}}}

                    {{{matrix(1,3, a[n], "=", a[1] + (n - 1)d)}}} ------ Formula for a specific term of an AP
                   {{{matrix(1,3, a[20], "=", 3 + (20 - 1)- 5)}}} ----- Substituting 20 for n, 3 for a<sub>1</sub>, and - 5 for d
AP's 20<sup>th</sup> term, or {{{highlight_green(matrix(1,7, a[20], "=", 3 - 5(19), "=", 3 - 95, "=", highlight(- 92)))}}}</pre>