# Assume y varies inversely as x," if " y=7 " when " x=6, how do you find y when x=-12?

Jul 29, 2017

$y = - 3.5$

#### Explanation:

Write the information as in inverse proportion first.

$y \propto \frac{1}{x}$

Make an equation by multiplying by the constant $k$

$y = \frac{k}{x} \text{ } \Rightarrow k = x y$

Find the value for $k$ from the information given.

$k = 6 \times 7 = 42$

$\therefore y = \frac{42}{x}$

Now find the required value of $y$:

$y = \frac{42}{-} 12$

$y = - 3.5$