Why do firms try to sell more products or to sell them at higher prices?

Even a simple understanding of economics and price theory will prove this. No matter the firm's market power, price is always set by supply and demand. They can try and command a price on their own, but competitors will find a way to sell the same thing at a lower price. Supply and Demand always dictate price...even in gas prices contrary to what the media would have you believe. If Americans quit using so mus gas, the price would drop. But we keep buying it up and the demand rises during the summer. Since there is only a fixed amount of the product available for the world, this increased demand forces the price up ...because somewhere, somebody is willing to pay it. And if nobody is willing to pay it, they will lower the price to encourage it. Now, what if the government forced them to lower the price. Suppose they set a limit at 2.00 cents a gallon. The result? There would never be enough gas to last. People would take the opportunity to fill up all their cars, their mowers, their gas cans, their boat...and then the guy who just needs a few gallons can't get any because everyone else bought it up due to an artificial price fix. Supply and demand are the factors that affect price. Not anything else. It's NOT a company's "greedy" desire for profit. In fact, big oil companies make only about 12 cents on each gallon of gas...the government taxes each gallon nearly 20 cents...so do the math. If X oil company posts a profit of 12 billion dollars, the media goes nuts and everybody calls them greedy...but that means the government just got 20 billion in taxes off the same gas. Instead of phony "price ceilings" let supply and demand have their way in the market.

To increase revenue. Revenue = Price x Quantity sold. So if a firm sells more products and/or sells products at a higher price, revenue will increase.

hope that helps