Question

For a direct variation if y=2 when x= -4, how do you find x when y=20?

Answer 1

`x=-40`

Explanation:

`"for direct variation"`

`"the initial statement is " ypropx`

`"to convert to an equation, multiply by k, the constant of variation"`

`rArry=kx`

`"to find k, use the condition given"`

`y=2" when " x=-4`

`rArr2=-4krArrk=2/(-4)=-1/2`

`"the equation is " y=-1/2x`

`"when " y=20`

`"then " x=20/(-1/2)=-40`