Let $f$ be a function satisfying $f(xy) = \frac{f(x)}{y}$ for all positive real numbers $x$ and $y.$ If $ f(30) = 20,$ then the value of $f(40)$ is-

Let $f(x) = \frac{{x\,\, – \,\,1}}{{2\,{x^2}\,\, – \,\,7x\,\, + \,\,5}}$ . Then :

The domain of the function $f(x) = {\sin ^{ – 1}}[{\log _2}(x/2)]$ is

If $f(x)$ is a quadratic expression such that $f(1) + f (2)\, = 0$ , and $-1$ is a root of $f(x)\, = 0$, then the other root of $f(x)\, = 0$ is

If $f(x + ay,\;x – ay) = axy$, then $f(x,\;y)$ is equal to