good explanations, formula, graphs , definitions used etc

Q3. Given the demand function q = i\": P i. For what values of a will this be a downward-sloping, elastic demand curve? ii. What is an expression for the price elasticity of demand for this function? Q4. The demand in a competitive industry is given by P = 500 4Q2, the supply is estimated to be P = Q2. The market is in equilibrium. Find the consumer surplus (CS)