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

Solution:

Consider the first term, common difference and number of terms of an AP are a, d and n.

We know that

First term (a) = 12

From the given condition,

7th term (T₇) = 11th term (T₁₁) - 24

The nth term of an AP, Tn = a + (n - 1 )d

⇒ a + (7 - 1)d = a + (11 - l)d - 24

⇒ a + 6d = a + 10d - 24

⇒ 24 = 4d

Dividing both sides by 4

⇒ d = 6

So the 20th term of AP,

T₂₀ = a + (20 - 1)d

Substituting the values

= 12 + 19 × 6

= 126

Therefore, the 20th term of an AP is 126.

✦ Try This: Find the 18th term of the AP whose 6th term is 12 less than the 10th term, the first term being 8

☛ Also Check: NCERT Solutions for Class 10 Maths Chapter 5

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NCERT Exemplar Class 10 Maths Exercise 5.3 Problem 8

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

Summary:

The 20th term of the AP whose 7th term is 24 less than the 11th term, first term being 12 is 126

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☛ Related Questions:

• Find whether 55 is a term of the AP: 7, 10, 13,— or not. If yes, find which term it is
• Determine k so that k²+ 4k + 8, 2k² + 3k + 6, 3k² + 4k + 4 are three consecutive terms of an AP
• Split 207 into three parts such that these are in AP and the product of the two smaller parts is 462 . . . .