Q2 of 84 Page 5

In an AP, if d = -2, n = 5 and a_n = 0, then the value of a is (CBSE 2011)

We know:

a_n = a + (n – 1)d

So,

0 = a + (5 – 1)(-2)

= a + 4(-2)

= a – 8

⇒ a = 8

If the common difference of an A.P. is 3, then a₂₀ – a₁₅ is (CBSE 2011)

The value of a₃₀ – a₂₀ for the A.P 2,7,12,17,….. is (CBSE 2011)

If nth term of an A.P. is (2n + 1), what is the sum of its first three terms? (CBSE 2012)

The sum of first 20 odd natural numbers is: (CBSE 2012)

In an AP, if d = -2, n = 5 and an = 0, then the value of a is (CBSE 2011)