If y varies directly with x, if y = 8 as x = -4 how do you find the direct variation equation?

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Answer 1 · 2016-08-22T17:45:18

$y+2x=0$

$8=-4k$

or

$k=constant=-8/4=-2$

Therefore we can write $y=-2x$

or

$y+2x=0$

Answer 2 · 2016-08-22T17:51:13

$x = -2y$

Write the given information in Maths first.

$x prop y" values which are in proportion to each"$
$color(white)(xxxxxxxxx)"other are connected by a constant."$

$color(red)(x = ky) color(white)(xxxxxxxxxxxx)" make an equation using k"$

$k = x/y = -4/8 = -2 color(white)(xxxxxxxxx) "find a value for k"$

Now put the value for 'k' into the equation.

$color(red)(x = -2y)$