AP EAMCET201726 Apr 2017Morning ShiftMathematicsBinomial TheoremActual
³⁷ C₄+ _ r=1 ^5(42-r)_ C_r =
Options
- A⁴¹ C₄
- B³⁹ C₄
- C³⁸ C₄
- D⁴² C₄
Correct answer
D. ⁴² C₄
Step-by-step solution
Given that, aligned & ³⁷ C₄+ _ r=1 ^5 ^ (42-r) C_r & = ³⁷ C₄+ ⁴¹ C₁+ ⁴⁰ C₂+ ³⁹ C₃+ ³⁸ C₃+ ³⁷ C₃ & = ³⁷ C₃+ ³⁷ C₄+ ³⁸ C₃+ ³⁹ C₃+ ⁴⁰ C₃+ ⁴¹ C₃ aligned As we know, aligned & ^n C_ r-1 + ^n C_r= ^ n+1 C_r & = ³⁸ C₄+ ³⁸ C₃+ ³⁹ C₃+ ⁴⁰ C₃+ ⁴¹ C₃ & = ³⁹ C₄+ ³⁹ C₃+ ⁴⁰ C₃+ ⁴¹ C₃ & = ⁴⁰ C₄+ ⁴⁰ C₃+ ⁴¹ C₃ & = ⁴¹ C₄+ ⁴¹ C₃= ⁴² C₄ aligned