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BITSAT2020MathematicsBinomial TheoremActual

If a, b, c are three natural numbers in AP and a + b + c =21 then the possible number of values of the ordered triplet ( a , b , c ) is

Options

  1. A15
  2. B14
  3. C13
  4. DNone of these

Correct answer

C. 13

Step-by-step solution

Let a=b-d and c=b+d , then a+b+c=21 b =7 So, the equation is a + c =14 No. of solution = coeff. of x¹⁴ in (x+x²+ . )= ¹³ C ₁₂=13

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