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If 43cr − 6 = 43c3r + 1 , Then the Value of R is (A) 12 (B) 8 (C) 6 (D) 10 (E) 14

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Question

If 43Cr − 6 = 43C3r + 1 , then the value of r is

Options

  • 12

  •  8

  •  6

  •  10

  • 14

MCQ
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Solution

12

\[r - 6 + 3r + 1 = 43\]  [∵ \[{}^n C_x =^n C_y \Rightarrow n = x + y or x = y\]]
\[\Rightarrow 4r - 5 = 43 \]
\[ \Rightarrow 4r = 48\]
\[ \Rightarrow r = 12\]
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Chapter 17: Combinations - Exercise 17.5 [Page 26]

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R.D. Sharma Mathematics [English] Class 11
Chapter 17 Combinations
Exercise 17.5 | Q 21 | Page 26

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