Question

It is known that the point P(-9,18) belongs to the graph of the function y=k/x. Find k.

Answer 1

Answer:

$k = (-162)$.

Step-by-step explanation:

A point of the form $(x_{0},\, y_{0})$ belongs to the graph of this function, $y = k / x$, if and only if the equation of this function holds after substituting in $x = x_{0}$ and $y = y_{0}$.

The question states that the point $(-9,\, 18)$ belongs to the graph of this function. Thus, the equation of this function, $y = k / x$, should hold after substituting in $x = (-9)$ and $y = 18$:

$y = k / x$.

$18 = k / (-9)$.

Solve this equation for the constant $k$:

$\begin{aligned}k &= 18 \times (-9) \\ &= (-162)\end{aligned}$.

Thus, $k = (-162)$.