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On March 11, 2024, 11:35 AM

Exercise 7.2 - Chapter 7 Permutations & Combinations class 11 ncert solutions Maths - SaraNextGen [2024]


Question 1:

Evaluate

(i) 8! (ii) 4! – 3!

Answer:

(i) 8! = 1 × 2 × 3 × 4 × 5 × 6 × 7 × 8 = 40320

(ii) 4! = 1 × 2 × 3 × 4 = 24

3! = 1 × 2 × 3 = 6

∴4! – 3! = 24 – 6 = 18

Question 2:

Is 3! + 4! = 7!?

Answer:

3! = 1 × 2 × 3 = 6

4! = 1 × 2 × 3 × 4 = 24

∴3! + 4! = 6 + 24 = 30

7! = 1 × 2 × 3 × 4 × 5 × 6 × 7 = 5040

∴ 3! + 4! ≠ 7!

Question 3:

Compute https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4211/chapter%207_html_350ec2ad.gif

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4211/chapter%207_html_8d46127.gif

Question 4:

If https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4212/chapter%207_html_329ae33a.gif, find x.

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4212/chapter%207_html_58a92582.gif

Question 5:

Evaluatehttps://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4213/chapter%207_html_m3aadba17.gif, when

(i) n = 6, r = 2 (ii) n = 9, r = 5

Answer:

(i) When n = 6, r = 2, https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4213/chapter%207_html_3f6b0689.gif

(ii) When n = 9, r = 5, https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4213/chapter%207_html_m76bcd6e3.gif

https://img-nm.mnimgs.com/img/study_content/curr/1/11/11/167/4213/chapter%207_html_17e8376c.gif

Also Read : Exercise-7.3-Chapter-7-Permutations-&-Combinations-class-11-ncert-solutions-Maths

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