This week for precalc11 we learned how to solve rational equations and use them to deal with some problems in reality. There’re a lot of different kinds of problems, such as problems involving distance, time and speed; problems involving work; and those others involving proportions…… For me, this is the part that I found challenging because there’re so many different items in every single question that I don’t know which items should I use to build the equations. For example, this time you should use speed, but the other time you should use the working hours. It’s also hard for me to understand the meanings of those questions, so I may take more time than others on this kind of questions.

Here’s a question that I got wrong on our book: The average speed of an airplane is 10 times that of a car. It takes the aorplane 18 h less thanthe car to travel 1000km. Determind the average speeds of the aorplane and the car.

I assumed the average speed of car as x, so the speed of airplane is 10x, so the equation is: 1000/x-18=1000/10x. The common denominator is 10x, I forgot to cancel the denominator, so I got x=1/18. That’s a silly mistake on calculating, but I always do it…… After asking for help, I got the right answer finally.

I hope I can get good result fo this chapter test. To do that, I must be careful with my calculating.