If a price-demand equation is solved for p, then price is expressed as p = g(x) and x becomes the independent variable. In this case, it can be shown that the g (x ) elasticity of demand is given by E(x) = - xg'(x ) Use the price-demand equation below to find the values of x for which demand is elastic and for which demand is inelastic. p = g(x) = 240 - 0.4x Demand is elastic for all x in the interval (Type your answer in interval notation.)