\(\frac{n(n-r)}{r}\)
\(\frac{n}{r(n-r)}\)
\(\frac{1}{r(n-r)}\)
\(\frac{n+1-r}{r}\)
Correct answer is D
\(^{n}C_{r} = \frac{n!}{(n-r)! r!}\)
\(^{n}C_{r - 1} = \frac{n!}{(n - (r - 1))! (r - 1)!}\)
\(^{n}C_{r} ÷ ^{n}C_{r - 1} = \frac{n!}{(n - r)! r!} ÷ \frac{n!}{(n-(r-1))!(r-1)!}\)
= \(\frac{n!}{(n-r)! r!} \times \frac{(n-(r-1)! (r-1)!}{n!}\)
= \(\frac{(n + 1 - r)! (r - 1)!}{(n - r)! r!}\)
= \(\frac{(n+1-r)(n-r)! (r-1)!}{(n-r)! r (r - 1)!}\)
= \(\frac{n + 1 - r}{r}\)
Find the coordinates of the centre of the circle \(4x^{2} + 4y^{2} - 5x + 3y - 2 = 0\)....
If \(3x^2 + p x + 12 = 0\) has equal roots, find the values of p ....
Given that \(P = \begin{pmatrix} y - 2 & y - 1 \\ y - 4 & y + 2 \end{pmatrix}\) and |P| = -2...
Evaluate \(\cos 75°\), leaving the answer in surd form....
The function \(f : F \to R\) = \(f(x) = \begin{cases} 3x + 2 : x > 4 \\ 3x - 2 : x = 4 \\ ...
Find the equation of the normal to the curve y= 2x\(^2\) - 5x + 10 at P(1, 7)...