Question 459465
{{{sum((a[1]+(n-1)d),n=beginning,end)}}}
{{{a[1]=-3}}}  
{{{d = a[2]-a[1]=(-1)-(-3) = -1+3 = 2}}}
{{{d = a[3]-a[2]=1-(-1) = 1+1 = 2}}}
{{{d = a[4]-a[3]=3-1 = 2}}}
{{{d = a[5]-a[4]=5-3 = 2}}}
{{{beginning = 1}}}
{{{end = 5}}}
{{{sum((-3+(n-1)*2),n=1,5)}}}
{{{sum((-3+2(n-1)),n=1,5)}}}
{{{sum((-3+2n-2),n=1,5)}}}
{{{sum((-5+2n),n=1,5)}}}
{{{sum((2n-5),n=1,5)}}}

Edwin</pre>