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BITSAT2016MathematicsBinomial TheoremActual

The number of values of satisfying the equation ³⁹ C _ 3 r -1 - ³⁹ C _ r ² = ³⁹ C _ r ²-1 - ³⁹ C _ 3 r is

Options

  1. A1
  2. B2
  3. C3
  4. D4

Correct answer

B. 2

Step-by-step solution

³⁹ C _ 3 r -1 - ³⁹ C _ r ² = ³⁹ C _ r ²-1 - ³⁹ C _ 3 r ³⁹ C _ 3 r -1 + ³⁹ C _ 3 r = ³⁹ C _ r ²-1 + ³⁹ C _ r ² ⁴⁰ C _ 3 r = ⁴⁰ C _ r ² r ²=3 r or r ²=40-3 r r =0,3 or -8,5 3 and 5 are the values as the given equation is not defined by r=0 and r=-8 . Hence, the number of values of r is 2 .

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