110k views
2 votes
The fourth term of an arithmetic

progression is one less than twice the
second term If the sixth term is 7,
find the first term​

1 Answer

2 votes

Answer:

2

Explanation:

Given AP where:

  • a₄ = 2a₂ - 1
  • a₆ = 7

To find

  • a₁ = ?

Since

  • a₄ = a₁ + 3d
  • a₂ = a₁ + d
  • a₆ = a₁ + 5d

Initial equations will change as:

  • a₁ + 3d = 2(a₁ + d) - 1 ⇒ a₁ + 3d = 2a₁ + 2d - 1 ⇒ a₁ = d + 1
  • a₁ + 5d = 7 ⇒ a₁ = 7 - 5d

Comparing the above:

  • d + 1 = 7 - 5d
  • 6d = 6
  • d = 1

Then:

  • a₁ = d + 1 = 1 + 1 = 2
  • a₁ = 2

The first term is 2

User Gourango Sutradhar
by
6.0k points