Question 856103
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Hi,
a1 = 36 and r = 1/2= .5
{{{a[n] = 36(.5)^(n-1)}}}  |.5| < 1
{{{sum( a[n],n=1, infinity )}}} = {{{a[1]/(1-r)}}}
{{{sum( 36(.5)^(n-1),n=1, infinity )}}} = {{{36/(1/2)}}} = 72