Question

Select the correct notations for combination

• A. ${}^n{C}_r$
• B. $\left({}_r^n\right)$
• C. $C{}_k^n$
• D. ${}_r{C}^n$
• E. $\left(nr\right)$
• F. ${}^{n}C{}^k$
• G. ${}_n{C}_r$
• H. $n{C}_r$
• I. $C{}_r^n$

Answer 1

Answer: (A), (B), (C), (G), (I)

$C{}_r^n$