If the 100th term of an arithmetic sequence is 287, and its common difference is 3, then

Question

If the 100th term of an arithmetic sequence is 287, and its common difference is 3, then

its first term a1 = ________

its second term a2 = ________

its third term a3 = _______

Hint: Use an =a1 + (n-1) d

Answer 1

a₁₀₀=287=a₁+(100-1)3

287=a₁+99(3)

a₁=287-297=-10

Than means:

a_n=-10+(n-1)3=-10+3n-3=3n-13

So:

a₂=3(2)-13= -7

a₃=3(3)-13=-4

And to validate the given:

a₁₀₀=3(100)-13=300-13=287