Question

What is the direct variation equation if f(x) varies directly with x and f(x) = –18 when x = 3?

Answer 1

`f(x)=-6x`

Explanation:

`"the initial statement is "f(x)propx`

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

`f(x)=kx`

`"to find k use the given condition"`

`f(x)=-18" when "x=3`

`f(x)=kxrArrk=(f(x))/x=(-18)/3=-6`

`"equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(f(x)=-6x)color(white)(2/2)|)))`