2. There are () white sheep and () black sheep in the sheepfold, because there are 20 fewer white sheep in the sheepfold and 20 fewer black sheep's heads than white sheep's feet 145.
3. A humorously said to B: "When I was your age, you were only 2 years old; And when you were my age, I was 38 years old. " Then the ages of A and B are () ().
4. If the equation about x MX 2+(m-2) x+5 = 0 is quadratic, then m=___.
5. Xiaoming went to a supermarket and bought two different brands of jelly, 4.5 yuan/kg and 6.5 yuan/kg. The unit price was m kg and n kg respectively. The average unit price of the jelly he was asked to buy was _ _ _ _ yuan/kg.
6. Please write down the conditions: one is x= 1 and the other is-1
7. The circle centered on the O point (0 as the origin of coordinates) intersects the inverse proportional function (passing through the first and third quadrants). If the coordinate of an intersection point is (5, 1), the sum of the areas of the image of the inverse proportional function and the figure surrounded by the circle is the sum of the areas of the small blocks on both sides of the first and third quadrants.
8. It is known that the solution set of inequality (A-2) with x greater than 2-a is that x is less than -4, so the value range of a is ().
Ball problem solving process
9. When a ship sails upstream in a river with a water flow speed of 3 km/h, its speed when sailing downstream is _ _ _ _ _ _ _ km/h..
10. Sector radius = 30cm, arc length = 36cm, and area = _ _ _ _ _ _ _ _ _
1 1. The middle radius of the sector = 20cm, the arc length = 40cm, and the area = _ _ _ _ _ _ _ _ _ _
12. Given that the central angle of the sector is 45, then the arc length of the sector is _ _ _ _ _ _ _ _ _ of the circumference of the sector (fill in a fraction).
13. If the equation about x MX 2+(m-2) x+5 = 0 is a quadratic equation, then m=___.
14. Xiaoming went to a supermarket and bought two different brands of jelly, namely 4.5 yuan/kg and 6.5 yuan/kg. The average unit price of the jelly he bought was _ _ _ _ yuan/kg.
15. Please write down the conditions: one is x= 1 and the other is-1
16. Cos α is known to be less than 0.5, so the range of acute angle α is _ _ _ _ _ _.
17. If someone advances C meters along a slope with an angle of α, then his rising height is _ _ _ _ _ _ _.
18. At the right angle △ABC, ∠ C = 90, CD⊥AB is in D, and AC=3 and AB=5 are known, then Tan ∠ BCD _ _ _ _ _
19. It is known that the total amount of several RMB denominated in 2 yuan and 5 yuan is 240 yuan, so the number of RMB denominated in 2 yuan is ().
20. It is known that ∠A = 5147', then the complementary angle of ∠ A is equal to _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
The fractional equation of 21.a-2x: _ _ _ _-1= 0 has no solution, and a = _ _ _ _ _ _ The fractional equation of x+4 is a-2x/ (instead of fractional line) x+4-1=0.
22. If both sides of the inequality 1+4x > 2-3x are added at the same time, 7x > 1 is obtained, based on _ _ _ _ _ _ _.
23. it is known that a > b and m < 0, then a+m _ _ _ _ _ b+m, according to the nature of inequality _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
24. Since the 1960s, the number of economic cooperation projects between Shanghai and Yunnan has reached 1300, with 53% actually completed. So, 1 of _ _ _ _ has actually been completed. Let a large number X be a decimal number Y, and let the equation X-Y = 29 and X = 3Y+5.
2. Let the white sheep have X heads and the black sheep have Y heads. Equation: X+20=4Y, Y+ 145=4X, the solution is X=40, Y= 15.
3. Let A be X years old and B be Y years old, then A is (X-Y) years older than B. The equation is: Y-(X-Y)=2, X+(X-Y)=38, and the solution is X=26, Y= 14.
4.m is not equal to 0 and (m-2) 2-20m > 0 (if there are two unequal real roots).
5.(4.5m+6.5n)/(m+n)
6. From the root system: 0
7.∵ Here, the inverse proportional function and the circle are graphs that are symmetrical about the center of the origin.
∴ Shadow area =πr? 0? 5/4
The coordinates of the intersection point are (5, 1)
∴r？ 0? 5=5? 0? 5+ 1? 0? 5=26
∴ Shadow area = 13π/2
8. The solution set of (a-2) x greater than 2-a is that x is less than -4, which should be "less than-1"?
The direction of the unequal sign changes, indicating A-2.
That is, a < 2.
9. In countercurrent, the sailing speed of a ship is the difference between the speed of the ship in still water and the speed of water, that is, a=v -3.
So, V boat =a+3.
When sailing downstream, the ship speed is the sum of the two, that is, V ship +3=a+6.
Answer: a+6
10.36/(2*3。 14*30)*3。 14*30*30 Note 3. 14 numerator and denominator cancel! The answer is 540.
1 1.400
12. A fillet is 360 degrees, so what is 45 degrees? 1/8
13.m is not equal to 0.
14.(4.5m+6.5n)/(m+n)
15. One is x= 1, and the other satisfies-1
0 & ltx 1+x2 & lt； 2
- 1 & lt； x 1 * x2 & lt； 1
One is x= 1, and the other satisfies-1
(X- 1)(X- 1/2)=0
X^2-3/2*X- 1/2=0
16.60 ——90
17.c*tanα
18.4/3
19.5n
20.38 13′ 128 13′ 166 1 1′3 1〃
2 1. Because (a-2x)/(x+4)- 1=0, when x is not equal to -4, there is -2x=x+4, that is, 3x=4-a, so x=(4-a)/3. In other words, the equation always has a solution. But from the meaning of the question, the equation has no solution, so the only solution mentioned above must be x=-4. Therefore, (4-a)/3=-4, that is, a= 16.
22. Add _ 3x _ _ _ _ to both sides of inequality 1+4x > 2-3x to get 7x > 1. According to the inequality _ _ _ _, both sides add the same number at the same time, and the direction of the inequality remains the same _ _.
23. given a > b and m < 0, a+m _ >; _ _ _ _ b+m, according to the nature of inequality _ Add the same number on both sides of inequality at the same time, and the direction of inequality remains unchanged _ _ _ _ _ _ _ _. AM _ _
24. 1300×53%=689。 689 items were actually completed.