Đề thi Olympic Tiếng Anh lớp 9 vòng 25 năm 2013 - 2014

If x < 0, which expression has a negative value?

Water flows into a tank at a constant rate. The table above shows the relationship between the amount of water in the tank and the time passed since the water began to flow. Based on the table, which equation shows the relationship between the amount, a , in liters, of water in the tank and t, the time, in minutes, after the water began to flow?

A computer is purchased for $1,200 and depreciates at $140 per year. Which linear equation represents the value, V, of the computer at the end of t years?

An object is dropped from a tall building. Suppose the distance it travels is given by the formula d = 16t2, where d represents the distance it drops in feet and t represents time in seconds. About how long does it take the object to fall 800 feet?

Henry wants to join a book-of-the-month club. The first club costs $40 to join and $10 per book. The second club costs $15 per book and has no fee to join. How many books would he need to purchase so that the costs are the same from the two clubs?

A group of 3 children and 2 adults pay a total of $120 to take a karate class. A group of 5 children and 1 adult take the same karate class for $95. What is the total cost for 1 child and 1 adult to take the karate class?

For the line y = mx + b, where m > 0 and b < 0, what change would occur if b is multiplied by -1 and m remains the same?

The Outboard Motor Company can produce 50 motors in 4 weeks. Assuming a direct variation, how many motors can the company produce in 10 weeks?

What is the greatest common factor of 63r²t³ and 42r³t⁵?

Simplify: a + 4(6a + 2b²) + (a² - 6b²)