Technical improvements cause production costs to decline, which causes ( demand , supply , income ) to increase and prices to ( increase , decrease , stay the same ) decreased unemployment causes consumer incomes to ( increase , decrease , stay the same ) , which causes ( demand , supply , prices ) to increase

When a company produces and sells x thousand units per week, its total weekly profit is p thousand dollars, where upper p equals startfraction 800 x over 100 plus x squared endfraction . the production level at t weeks from the present is x equals 4 plus 2 t. find the marginal profit, startfraction dp over dx endfraction and the time rate of change of profit, startfraction dp over dt endfraction . how fast (with respect of time) are profits changing when tequals8?