Question

What is a 217 for the sequence -10,-7, -4,-1, ...

Answer 1

a(217)=638

Explanation:

a(n) = a +(n-1)d

a=-1

d=-7+10=-4+7=3

a(n) = -10 +(n-1)3

a(217) = -10 +(217-1)3

= -10+648

=638

hope this helps