Question

Finf r if C(11,2r)=C(11,r+5)

Answer 1

Answer:

The answer is $r=5,2$

Step-by-step explanation:

• We know that  $C(n,x)=C(n,y)\Rightarrow x=y \text{ or } x+y=n$

             Here given $C(11,2r)=C(11,r+5)$

                     $\Rightarrow 2r=r+5 \text{ or } 2r+r+5=11\\\Rightarrow 2r-r=5 \text{ or } 3r=11-5=6\\\Rightarrow r=5 \text{ or } r=\frac{6}{3}=2$