I was trying to solve the equation using factorial as shown below but now I'm stuck at this level and need help.
$$C(n,3) = 2*C(n,2)$$
$$\frac{n!}{3!(n-3)!} = 2\frac{n!}{2!(n-2)!}$$
$$3! (n - 3)! = (n - 2)!$$
I was trying to solve the equation using factorial as shown below but now I'm stuck at this level and need help.
$$C(n,3) = 2*C(n,2)$$
$$\frac{n!}{3!(n-3)!} = 2\frac{n!}{2!(n-2)!}$$
$$3! (n - 3)! = (n - 2)!$$
$$\require{cancel} \frac{n!}{3!\cdot(n-3)!} = 2\cdot\frac{n!}{2!\cdot(n-2)!}$$
Dividing by $n!$ and collecting constants:
$$\frac{1}{(n-3)!} = \frac{6}{(n-2)!}$$
$$6=\frac{(n-2)!}{(n-3)!}=\frac{(n-2)\cancel{(n-3)(n-4)(n-5)...}}{\cancel{(n-3)(n-4)(n-5)...}}$$
$$6=n-2$$
$$\therefore n=8$$