Question

If the first term in an arithmetic sequence is –3 and the tenth term is 15, what is the common difference?

Answer 1

Given that the First term of the Arithmetic sequence = -3

⇒ a = -3

We know that nth term of a Arithmetic sequence is : Tn = a + (n - 1)d

where a is the first term and d is the common difference

Given that 10th term is 15

⇒ T₁₀ = -3 + (10 - 1)d

⇒ -3 + (10 - 1)d = 15

⇒ 9d = 18

⇒ d = 2

⇒ Common difference of given Arithmetic Sequence is 2