Q8 of 89 Page 51

Find the 20th term of the AP whose 7th term is 24 less than the 11th term, first term being 12.

Let the a be first term and d be common difference

As we know

a_n = a + (n - 1)d

Given,

a₇ = a₁₁ - 24

a + 6d = a + 10d - 24

10d - 6d = 24

4d = 24

d = 6

given a = 12

then, a₂₀ = a + 19d

a₂₀ = 12 + 19(6)

= 12 + 114

= 126

The 26th, 11th and the last terms of an AP are, 0, 3 and respectively.

Find the common difference and the number of terms.

The sum of the 5th and the 7th terms of an AP is 52 and the 10th term is 46. Find the AP.

If the 9th term of an AP is zero, then prove that its 29th term is twice its 19th term.

Find whether 55 is a term of the AP, 7, 10, 13, … or not. If yes, find which term it is.