Q5 of 178 Page 559

If the nth term of an AP is (2n + 1), then the sum of its first three terms is

Given: n^th term = 2n + 1

∴ a_n = 2n + 1

Put n= 1, a₁ = 3

Put n= 2, a₂ = 5

Put n= 3, a₃ = 7

Now, sum of first three terms = 3 + 5 + 7 = 15

The next term of the AP is

If 4, x₁, x₂, x₃, 28 are in AP then x₃ = ?

The sum of first n terms of an AP is (3n² + 6n). The common difference of the AP is

The sum of first n terms of an AP is (5n – n²). The nth term of the AP is