Example 5 - Determine AP whose 3rd term is 5 and 7th term

Example 5 - Chapter 5 Class 10 Arithmetic Progressions - Part 2
Example 5 - Chapter 5 Class 10 Arithmetic Progressions - Part 3

Take a fresh quiz. Then take another.
Every attempt is a new AI-adaptive Teachoo quiz with 3 questions, selected from your answers, mistakes, and progress.
Remove Ads

Transcript

Example 5 Determine the AP whose 3rd term is 5 and the 7th term is 9. We know that an = a + (n – 1)d From (1) & (2) 5 – 2d = 9 – 6d 6d – 2d = 9 – 5 Given 3rd term is 5 a3 = a + (3 – 1)d 5 = a + 2d a = 5 – 2d Given 7th term is 9 a7 = a + (7 – 1)d 9 = a + 6d a = 9 – 6d 4d = 4 d = 4/4 d = 1 Putting d = 1 in (1) a = 5 – 2d a = 5 – 2(1) a = 5 – 2 a = 3 Hence , First term of an A.P = 3 Second term of AP = First term + Common Difference = 3 + 1 = 4 Third term of AP = Second term + Common Difference = 4 + 1 = 5 So the A.P is 3, 4, 5, …………

Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh is an IIT Kanpur graduate and has been teaching for 16+ years. At Teachoo, he breaks down Maths, Science and Computer Science into simple steps so students understand concepts deeply and score with confidence.

Many students prefer Teachoo Black for a smooth, ad-free learning experience.