Answer :
Given, nCr–1 = 36, nCr = 84 and nCr+1 = 126
To find:r=?
⇒
⇒
⇒
⇒3(n-r+1)=7r
⇒3n-10r=-3….(1)
⇒
⇒
⇒
⇒2(n-r)=3(r+1)
⇒2n-5r=3….(2)
From equations 1 & 2 we get
n=9 & r=3
Ans:r=3
Rate this question :
How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
view all courses
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
RELATED QUESTIONS :
Prove that the pr
RD Sharma - MathematicsThere are 10 lamp
Mathematics - ExemplarIf n+1
RS Aggarwal - MathematicsIf nC<
RS Aggarwal - MathematicsFill in the Blank
Mathematics - ExemplarFill in the Blank
Mathematics - ExemplarThe number of way
Mathematics - ExemplarTotal number of w
Mathematics - ExemplarThe number of way
Mathematics - ExemplarThe number of tri
Mathematics - Exemplar