Question 966984
a) First term is zero. Add  -5 to each successive term.
{{{A[n]=A[0]+(n-1)d}}}
{{{A[n]=0+(n-1)(-5)}}}
{{{A[n]=-5n+5}}}
{{{A[n]=5-5n}}}
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b) First term is -18. Add 2 to each successive term.
{{{A[n]=-18+(n-1)(2)}}}
{{{A[n]=-18+2n-2}}}
{{{A[n]=2n-20}}}