Question

If the first term of an A.P. is – 18 and its 10th term is zero, then find its common difference.

Answer 1

First term (a) = –18
T₁₀ = 0
a + (n – 1)d = T_n
–18 + (10 – 1)d = 0
–18 + 9d = 0
⇒ 9d = 18
⇒ d = `(18)/(9)` = 2
∴ Common difference = 2.