if y= - 6 when x= 9, find x when y= - 3
We need to find the constant of variation, k, in this equation
y = kx and we know that
-6 =k9 divide both sides by 9
-6/9 = -2/3 = k
So......when y = -3, we have
-3 = (-2/3) x multiply both sides by -3/2
(-3/2) * -3 = x = 9/2
For a simple direct ratio problem, Chris is right. BUT if the variables are related by a more complex definition, like for example:
y = 2x - 24 the problem will need more information. For something like this, when x = 9 y= -6 BUT when y = -3 , x= 10.5
