50 extra points for math problems!! 50 points for math problems, urgent !!

1. A semicircle with a diameter of 4 cm, its circumference is ( ) cm.

The circumference of the semicircle is 2 diameters.

4 cm. 2. If the circle is divided into several parts from the center of the circle and put together into an approximate rectangle, the length of the rectangle is equivalent to the circle (half of the circumference), and the width of the rectangle is equivalent to the circle (radius).

It's 50 ( ) 40 50 80

50 is 40 ( ) 50 40 125

40 is less than 50 ( ) 50 40) 50 20 50 is more than 40 ( ).

4. The actual production of TV in the TV workshop is 10% more than planned, which is to take (the number of TVs planned to be produced) as the unit "1".

5. The canteen uses 1/5 of the ton of coal every day and 3 tons of coal for 3 days;

1/5 3 3/5 tons.

Use 1/5 of a pile of coal every day, and share ( ) 1/5 3 5/5 of this pile of coal for 3 days

6. When a(>1), 1/8 times a is greater than 1/8; When a(<1), 1/8 multiplied by a is less than 1/8.

1/4 of a number is 6/9 less than 4/9 of a number, and this number is ( ) 120 1/4 6) 4/9 81

2.Radius Half the circumference.

4.Planned production.

6.Greater than 1 is less than 1

1 cm.

2 Circumference Half Radius.

4 Plan the amount of television production.

5 3/5 tons 3/5

6 a is greater than 1 a is less than 1

1) 2) The length is equivalent to half the circumference of the circle, and the width is equivalent to the radius.

3) 40 is (80)% of 50, 50 is (125)% of 40, 40 is less (20)% less than 50, 50 is more (25)% than 40.

4) Take the plan as a unit "1".

5) 3 5 tons; 3/5。

6) When a (greater than 1), 1/8 times a is greater than 1/8; When a (less than 1), 1/8 times a is less than 1/8.

According to the square direction, it can be measured with a scale when used as a diagram.

First draw a drawing according to the prompts, and the requirements are also measured with a scale, according to the two angles of the direction of the Qing Lu guess the degree of the extension line intersects, get the C point, and then use the scale to measure it directly.

Connect the three points to form a triangle. The distance between the CD is measured by the known conditions, and the distance between the AC is twice that of the CD, so the distance between the CD is four times the distance between the CD and the 100-meter starting point A.

Traveling in the same direction: If the body length of the passenger car is x, the body length of the train is 140+x, therefore:

x+140+x=(90-60)*1 60*1000 gives x=180m

140+x=320m

Therefore, the body length of the passenger car is 180m, and the length of the truck is 320m, which travels in opposite directions. Let the crossing time be y.

320m+180m=(90+60)*y*1000 gets x=1 300h=1 5min=12s, so when the two cars are driving in the opposite direction, the crossing time is 12 seconds.

x/1*2+x/2*3+..x 2007*2008=2007 Solution: x(1 1*2+1 2*3+..1 2007*2008) = 2007 (bring x out).

x(1-1/2+1/2-1/3++.1 2007-1 2008) = 2007 (formalizes the denominator product of fractions into fractional differences).

x(1-1 2008) = 2007 ( middle terms are offset, only the first and last two terms remain) x (2007 2008) = 2007

x=2008

2010*(1-1/2)*(1-1/3)**1-1/4)*.1-1/2010)

Here the denominator of the previous fraction is exactly the numerator of the latter fraction can be reduced, so in the end only 1 2010 remains, so the answer is 1

Let's say change the number to 60

Are you just playing tricks?

The first method is the simplest and feasible and can be adopted.

1. 1 2 (m-6) + 4-(-4).

2. "3. D4*(X-3)<=20

Find the solution set for the following inequality.

x 7 has 3/4 - 4 has 1/2 =

x (-2) (14) = 1 7 multiply by dividing negative numbers by variable sign) x<(1 3) (3) = -1 9).

x<0x>(1/3)/(3/2)=2/9

2x>-1-7=-8 x>-8 2=-4 Countless, countless, countless.

I.1(m-6) +4 m in half

2. 2(y-2)≤0

3.2/3a + 5 4 II

III. 1 d 2.4(x-3) 20 If you learn the math, you have to calculate: 4x-12 20 4x 20+12 4x 32x 8

II, 1Less than 2, less than 3Greater than 4Less than three, multiple-choice.