jee-main 2019 Q63

jee-main · India · session1_10jan_shift2 Combinations & Selection Combinatorial Identity or Bijection Proof
If $\sum _ { r = 0 } ^ { 25 } \left\{ \left( { } ^ { 50 } C _ { r } \right) \left( { } ^ { 50 - r } C _ { 25 - r } \right) \right\} = K \left( { } ^ { 50 } C _ { 25 } \right)$, then $K$ is equal to
(1) $2 ^ { 25 }$
(2) $2 ^ { 25 } - 1$
(3) $2 ^ { 24 }$
(4) $( 25 ) ^ { 2 }$
If $\sum _ { r = 0 } ^ { 25 } \left\{ \left( { } ^ { 50 } C _ { r } \right) \left( { } ^ { 50 - r } C _ { 25 - r } \right) \right\} = K \left( { } ^ { 50 } C _ { 25 } \right)$, then $K$ is equal to\\
(1) $2 ^ { 25 }$\\
(2) $2 ^ { 25 } - 1$\\
(3) $2 ^ { 24 }$\\
(4) $( 25 ) ^ { 2 }$