Maths · Meaning of P(n,r) and C(n,r)
If then
If \( ^{n} C_{3}=^{n} C_{9}, \) then \( ^{n} C_{2}= \)
- A. 66
- B. 132
- C. 72
- D. 98
Step-by-step solution
Using the property nCr = nC(n-r), we have nC3 = nC9 implies n-3=9, so n=12. Then nC2 = 12C2 = 66.
Maths · Meaning of P(n,r) and C(n,r)
If \( ^{n} C_{3}=^{n} C_{9}, \) then \( ^{n} C_{2}= \)