Question

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

Answer 1

`y+2x=0`

Explanation:

`8=-4k`

or

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

Therefore we can write `y=-2x`

or

`y+2x=0`

Answer 2

`x = -2y`

Explanation:

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)`