Comments by usher

​​If, for non-zero real variables $x, y$, and real parameter $a>1$,\[x: y=(a+1):(a-1) \text {, }\]then, the ratio $\left(x^{2}-y^{2}\right):\left(x^{2}+y^{2}\right)$ is$2...

If $\text{P, Q, R, S}$ are four individuals, how many teams of size exceeding one can be formed, with $\text{Q}$ as a member?$5$$6$$7$$8$