Question 1131527

The nth term of an arithmetic sequence is:

{{{a[n]=a[1]+(n-1)d}}}

if the first term of an arithmetic sequence is {{{-3}}} and the fifteenth term is {{{53}}}, we have

{{{a[1]=-3}}}
{{{a[15]=53}}}
{{{n=15}}}

so, 

{{{53=-3+(15-1)d}}}

{{{53+3=14d}}}
 
{{{56=14d}}}

{{{d=56/14}}}

{{{d=4}}}=> the common difference of the sequence