(16) (n 2) ise C(n, 2) kagtr?

The given equation is:<br /><br />\[<br />\begin{pmatrix} \lambda \\ x \end{pmatrix} = \begin{pmatrix} n \\ 9 \end{pmatrix}<br />\]<br /><br />This implies that \( \lambda = n \) and \( x = 9 \).<br /><br />The question asks for \( C(n, 2) \), which is the number of combinations of choosing 2 elements from a set of \( n \) elements. The formula for combinations is:<br /><br />\[<br />C(n, 2) = \frac{n!}{2!(n-2)!}<br />\]<br /><br />Since \( \lambda = n \), we can substitute \( n \) for \( \lambda \):<br /><br />\[<br />C(n, 2) = \frac{n!}{2!(n-2)!}<br />\]<br /><br />This simplifies to:<br /><br />\[<br />C(n, 2) = \frac{n(n-1)}{2}<br />\]<br /><br />So, the correct answer is:<br /><br />\[<br />C(n, 2) = \frac{n(n-1)}{2}<br />\]