Question 612396
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi, 

find the formula for the partial sum of the first n termsof the following sequence
-2+0+2+4+...+(2n-4)
Note: {{{S[n]=(n(a[1]+a[n]))/2}}}
{{{S[n]=(n(-2 + (2n-4)))/2}}}
{{{S[n]= ((-2n + 2n^2-4n))/2)}}}
{{{S[n]= (( 2n^2-6n))/2)}}}
{{{S[n]= (2n(n-3))/2)}}}
{{{S[n]=  n(n-3)}}}