Suppose that y varies inversely with x. Write a function that models the inverse function. x = 7 when y = 3?

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Answer 1 · 2017-03-27T11:42:46

$y = \frac{21}{x}$ $y=21/x$

Inverse variation formula is $y = \frac{k}{x}$ $y=k/x$ , where k is the constant and $y = 3$ $y=3$ and $x = 7$ $x=7$ .

Substitute $x$ $x$ and $y$ $y$ values into the formula,

$3 = \frac{k}{7}$ $3=k/7$

Solve for k,

$k = 3 \times 7$ $k=3xx7$
$k = 21$ $k=21$

Hence,

$y = \frac{21}{x}$ $y=21/x$

Answer 2 · 2017-03-27T11:44:44

$y = \frac{21}{x}$ $y = 21/x$

$y = k \cdot \frac{1}{x}$ $y = k * 1/x$ , where $k$ $k$ is a constant.

$x = 7, y = 3$ $x = 7, y = 3$ , then

$3 = k \cdot \frac{1}{7}$ $3 = k * 1/7$

multiply with $7$ $7$ to both sides.

$7 \cdot 3 = k \cdot \frac{1}{7} \cdot 7$ $7 * 3 = k * 1/7 * 7$

$21 = k$ $21 = k$

therefore it equation is

$y = 21 \cdot \frac{1}{x} = \frac{21}{x}$ $y = 21 * 1/x = 21/x$