Inverse Proportion

In the previous post we basically defined direct proportion as what we do to x, we must also do to y. Specifically we said that if you double x, then we must double y to maintain the relationship as directly proportional. With inverse proportion when we double y we must halve x. The equation xy=k where k is the constant. For example suppose when x=3 y=20. If x is doubled to equal 6, y must be cut in half to 10 to maintain an inverse relationship. Using our equation xy=k we first solve for k--(3)20=60 so k=60; if we double x from 3 to 6 then we have 6y=60; y=10. So when x is doubled from 3 to 6, y is halved from 20 to 10. Simple as that.