Question

In an A.P 4th term is equal to 5 times of first term , 8th term is one more than twice the 4th term
Find the arithmetic progression.​

Answer 1

Step-by-step explanation:

A4 = 5 A1 -------------1

A8 = 1 + 2A4----------2

A1 = a

A4 = a + 3d

putting in equation 1

a+3d = 5a

3d = 4a----------3

A8 = a+7d

putting in equation 2

a+7d = 1+ 2(a+3d)

a+7d = 1+ 2a +6d

d = 1 + a------- 4

putting 4 in 3

3(1+a) = 4a

3 +3a =4a

a = 3

now from 4 we get

d= 1+ a

= 4

Ap = A1,A2 ,A3

A2 = a+ d

= 7

A3 = a+2d

= 3 + 2(4)= 11

AP = 3 , 7 ,11