Question

The 7th term of an A.P. is 20 and its 13th term is 32. Find the A.P.

Answer 1

The AP is 8, 10, 12, 14........

Given:

The 7th term of the Ap

The 13th term of the Ap

We can write the 7th term of the Ap:

a + 6d = 20 ----------Equation 1

We can write the 13th term of the Ap:

a + 12d = 32 -----------Equation 2

Solving both these Linear Equations by elimination method:

Subtracting both the equations we get:

a + 6d = 20

a + 12d = 32

  - 6 d = - 12

  d = - 12 / - 6

  d = 2

Therefore, common difference of the AP is 2.

Substituting the value of d in Equation 2:

a + 12 x 2 = 32

a + 24 = 32

a = 32 - 24

a = 8

Therefore, the first term of the AP is 8

Therefore, the AP is 8, 10, 12, 14........