Question

The sum of the 3^rd and 8^th term of an A.P. is 7 and the sum of the 7^th term and 14^th term is –3. Find the 10^th term of the A.P. 

(1) –1 

(2) +1 

(3) 0 

(4) 2

Answer 1

(1) –1 

a₃+ a₈ = 7 ⇒ a + 2d + a 7d = 7

⇒ 2a +9d =7

Also

a₇ + a₁₄ = -3  (i)

2a+19d = -3  (ii)

From (ii) and (i),

10d = -10

d = -1

\(a=\frac{7+9}{2}=8\)

 ∴  a₁₀ = a +9d = 8-9 = -1