Question
Question: If \(17C_{2r + 1} =^{17}C_{3r - 5}\), then \(\frac{6}{36} = \frac{1}{6}\)....
If 17C2r+1=17C3r−5, then 366=61.
A
20
B
18
C
30
D
16
Answer
20
Explanation
Solution
(i) 2r + 1 = 3r - 5
6 = r
rC3=6C3=3x26x5x4=20.
(ii) 2r + 1 + 3r - 5 = 17.
5r = 21 r = 21/5 (not possible).