Question

Consider an A.P a₁ , a_{2 ,} a_{3 ,}..... such that a₃ + a₅ + a₈ = 11 and a₄ + a₂ = -2 , then value of a₁ + a₆ + a₇ is 

(a) -8  (b) 5  (c) 7  (d) 9

Answer 1

Correct option is (c) 7

Given that,

a₃​ + a₅​ + a₈​ = 11

⇒ a + 2d + a + 4d + a + 7d = 11

⇒ 3a + 13d  =11   .....(1)

Given,

a_4​ + a_2​ = 2

⇒ a + 3d + a + d = −2

⇒ a =− 1 −2d   ......(2)

Putting value of a from (2) in (1), we get

3(−1 −2d) + 13d = 11

⇒ 7d = 14

⇒ d = 2 and a = −5

⇒ a₁​ + a₆​ + a₇​ = 7