Merging man & maths https://www.mathcity.org/ Thu, 04 Jun 2026 19:54:47 +0000 FeedCreator 1.8 https://www.mathcity.org/_media/logo.svg https://www.mathcity.org/ https://www.mathcity.org/math-11-nbf/sol/unit06/ex6-1-p7 Question 7(i-vi), Exercise 6.1 Solutions of Question 7(i-vi) of Exercise 6.1 of Unit 06: Permutation and Combination. This is unit of Model Textbook of Mathematics for Class XI published by National Book Foundation (NBF) as Federal Textbook Board, Islamabad, Pakistan. $n$$\quad \dfrac{n!}{(n-2)!}=930,\quad n \geq 2$\begin{align*} \dfrac{n!}{(n-2)!}&=930\\ \dfrac{n(n-1)(n-2)!}{(n-2)!}&=930\\ n(n-1)&=930\\ n^2-n-930&=0 \end{align*}\begin{align*} n&=\dfrac{1\pm \sqrt{1+4(930)}}{2}\\ &=\dfrac{1\pm … anonymous@undisclosed.example.com (Anonymous) Sat, 08 Mar 2025 08:59:37 +0000 https://www.mathcity.org/math-11-nbf/sol/unit06/ex6-1-p8 Question 7(vii-xi), Exercise 6.1 Solutions of Question 7(vii-xi) of Exercise 6.1 of Unit 06: Permutation and Combination. This is unit of Model Textbook of Mathematics for Class XI published by National Book Foundation (NBF) as Federal Textbook Board, Islamabad, Pakistan. $n$$\quad n!=990 \cdot (n-3)!$\begin{align*} n!&=990 (n-3)!\\ n(n-1)(n-1)(n-3)!&=990 (n-3)!\\ n(n-1)(n-1)&=990 \\ n^3-3n^2+2n-990 &=0\\ \end{align*}\[\begin{array}{c|cccc} & 1 & -3 & 2 & -990 \\ 11 & 0 & 11 & 88 & 990 \\… anonymous@undisclosed.example.com (Anonymous) Sat, 08 Mar 2025 08:59:36 +0000 https://www.mathcity.org/math-11-nbf/sol/unit06/ex6-3-p2 Question 1(vi-x), Exercise 6.3 Solutions of Question 1(vi-x) of Exercise 6.3 of Unit 06: Permutation and Combination. This is unit of Model Textbook of Mathematics for Class XI published by National Book Foundation (NBF) as Federal Textbook Board, Islamabad, Pakistan. $n\in N$$\quad^{2n}C_n=\dfrac{2^n[1.3.5.\cdots(2n-1)]}{n!}$\begin{align*}L.H.S &=\quad^{2n}C_n \\ &=\dfrac{(2 n)!}{n!(2 n-n)!}\\ &=\dfrac{(2 n)(2 n-1)(2 n-2)(2 n-n)(2 n-(n+1)) ..2 .1}{n!\cdot n!}\\ &=\dfrac{(2 n)(2 n-1)(2 n-2) ..(… anonymous@undisclosed.example.com (Anonymous) Sat, 08 Mar 2025 09:00:26 +0000