The multiple-choice question 1 is called a.
a、a+5 & gt； b+ 5； b、3a & gt3b； ; c 、- 5a & gt-5b； Diameter, 0.5a >0.5 billion
2. According to statistics, in 2009, under the strong impact of the international financial crisis, China's GDP was about 30,067 billion yuan, an increase of 9.0% over the previous year. 300670000000000 yuan is expressed by scientific counting method as (three significant figures are reserved) (d).
A, 3.0037× 10 13 yuan
B, 3.00× 10 13 yuan.
C, 30. 1× 10 12 yuan.
D, 3.0 1× 10 13 yuan.
3. Among the following statements, the correct one is (a).
A. straight line AB and straight line BA are the same straight line;
B. ray OA and ray AO are the same ray;
C. extend the line segment AB to point c so that AC = BC.
D. Draw a straight line AB = 5cm.
4. Given x ~ 2y =1,the value of algebraic expression 1-2x+4y is (d).
Answer, 3
b、0？
c 、- 1
d 、-3
Fill in the blanks 1. The number represented by a point whose distance from the point representing-1 on the number axis is equal to two unit lengths is (-3 or 1).
2. When aiming with a toy gun, the child always aims at the sight and the target with one eye, which is interpreted by mathematical knowledge as: (two points determine a straight line).
3. If the equation (a-1) x-2 = 3 is a linear equation about x, then the value of a is (-1).
4. Drive eastward for 3km, marked as+3 km; Drive west for 2 kilometers and mark it as (-2) kilometers.
answer the question
One day, Xiao Ming and Dong Dong used the temperature difference to measure the height of the mountain peak. The temperature measured at the foot of the mountain in winter and winter is 4℃, and that measured at the top of the mountain by Xiaoming is 2℃. It is known that the temperature drops by 0.8℃ every time the height in this area rises 100 meters. How high is this mountain?
Answer: 250 meters.
The above are the key math problems I have sorted out, and I hope they will help you.