Question

The 14th term of Apis twice its 8th Term of its 6th term
is 22 then find the sum of its first 10 term​

Answer 1

Answer:

Given, a14 = 2( a8 )

a6 = 22

a + ( 6-1)d = 22

a + 5d = 22 ----------------(1)

a14 = 2( a8 )

a + 13d = 2( a + 7d )

a + 13d = 2a + 14d

=> a + d = 0 --------------(2)

Subtract (2) from (1) we get

4d = 22

=> d = 11/2

put this value in equation (2) we get

a = - 11/2

now, according to question :

S10 = (10/2)[ 2×-11/2 + (10-1)(11/2) ]

= 5[ -11 + 99/2 ]

= 5( 77/2)

= 385/2