Question

Find

a
and
d
for an arithmetic sequence where the 5th term is 10 and the 6th term is 8.

Answer 1

Explanation:

Arithmetic sequence:

`\boxed{a_n =a + (n-1)*d)}`

a₅ = 10 a + 4d = 10

a₆ = 8 a + 5d = 8

Multiply the equation (I) by (-1) and then add. 'a' will be eliminated and we can find the value of 'd'

(I)*(-1) -a - 4d = -10

(II) a + 5d = 8 {Now add}

d = -2

Substitute d = -2 in equation (I)

a + 4*(-2) = 10

a - 8 = 10

a = 10 + 8

a = 18

a = 18 , d = -2

Sequence: 18 ,16 , 14 , 12 , 10 , ......