How do you find an equation of variation where y varies directly as x and y = 2 when x = 10, find y when x = -25?

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Answer 1 · 2016-07-21T19:33:11

$y = - 5$ $y = -5$

When dealing with variation (or proportion), start by writing down what is given, ie there is a relationship between $y and x$ $y and x$

$y \propto x$ $ypropx$

This can be written as an equation by using a constant.

$y = k x$ $y = kx$

$k = \frac{y}{x} Use the given values to find k$ $k = y/x" Use the given values to find" k$

$k = \frac{2}{10} = \frac{1}{5} Write the equation with k$ $k = 2/10 = 1/5" Write the equation with k"$

$y = \frac{1}{5} x Now you can find any value$ $y = 1/5 x" Now you can find any value"$

If $x = - 25, y = (\frac{1}{5}) \times - 25$ $x = -25, " " y = (1/5) xx -25$

$y = - 5$ $y = -5$