Question 1056567
Use any suitable method to find the sum of
63+68+73+...+103+108
<pre>Number of terms (n) in the sequence: {{{n = (a[n] - a[1])/d + 1}}}, where:
{{{a[n]}}} is the last term
{{{a[1]}}} is the 1st term
d is the common difference</pre><pre>
{{{n = (a[n] - a[1])/d + 1}}} now becomes: {{{n = (108 - 63)/5 + 1}}}_____{{{n = (45/5 + 1)}}}
n, or number of terms = 9 + 1, or 10

Sum of an AP formula: {{{S[n] = (n(a[1] + a[n]))/2}}}
{{{S[10] = (10(108 + 63))/2}}}____{{{S[10] = 5(171)}}}
Sum of the AP, or {{{highlight_green(matrix(1,3, S[10], "=", 855))}}}