①ab^2- ab(b-a)+(-2a)^2 ·x ②1/3 x(-x^2 +2x-1 )-1/3x^2(2x-6x^2)

①ab^2- ab(b-a)+(-2a)^2 ·x ②1/3 x(-x^2 +2x-1 )-1/3x^2(2x-6x^2)

①ab^2- ab(b-a)+(-2a)^2 ·x
=ab^2-ab^2-a^2b+4a^2X
=-a^2b+4a^2X
②1/3 x(-x^2 +2x-1 )-1/3x^2(2x-6x^2)
=-1/3x^3+2/3x^2-1/3x-2/3x^3+2x^4
=2x^4-x^3+2/3x^2-1/3x

1. Move point B from the position of each unit length on the number axis away from the far point 4 to the direction of the origin at the speed of 3 unit lengths per second for another 5 seconds to reach point A. calculate the number of point a on the number axis at this time
2. Fill in the five numbers - 7, - 3,1,5,9 in the box as shown in the figure to make the sum of the numbers in the horizontal and vertical directions equal. How do you fill in? (fill in at least three)
3.1-2+3-4+5-6+… +2009-2010+2011=_____ .
4. Calculation: 1 / 2 + 1 / 6 + 1 / 12 + 1 / 20 + 1 / 30 + 1 / 42 + 1 / 56 + 1 / 72 + 1 / 90=______ .
5. The product of all integers whose absolute value is less than 2010 is______ .
6. Calculation (1-2) (2-3) (3-4) (2009-2010)______ .
7. When the height of a certain place increases by 1000m, the temperature will decrease by about 6 ℃. The temperature of the high altitude balloon measured today is - 3 ℃, and the temperature of the ground is - 3 ℃. Calculate the height of the balloon

1 11 or - 11 2. The middle is 1 horizontal - 7 9 vertical - 3 5 horizontal vertical reverse, and the middle is 9 horizontal - 7 5 vertical - 3 1. Similarly, the middle is - 7 horizontal 1 5 vertical - 3 93 1-2, so there are 1005 groups in 2009-2010, the total is - 1005 + 2011 = 10064. The original formula can be changed to 1 / 1 * 2 + 1 / 2 * 3 + 1 / 3 * 4.1 /

On the multiplication and division of integral in mathematics of grade one
Ji Xiaoming is doing a math problem (x-1) (x + 1) (X & # 178; + 1) (x ^ 4 + 1) = (X & # 178; - 1) (X & # 178; + 1) (x ^ 4 + 1) = (x ^ 4-1) (x ^ 4 + 1) = x ^ 6-1. Then he compiles a problem (2 + 1) · (2 & # 178; + 1) · (2 ^ 4 + 1) (2 ^ 8 + 1) · (2 ^ 64 + 1) for TM

Add (2-1) before
Finally = (2 ^ 128-1)

1. A soldier received an order to perform a task from area a to area B within 3 hours. In actual walking, the soldier's speed was 2km per hour, which was half an hour earlier than the planned speed. What's the distance between a and B?
2. Xiaoming and Xiaobin decided to start at 8 a.m. in advance when they went for an outing by bike. They expected to ride 7.5 kilometers per hour and arrive at their destination at 10 a.m. before departure, they decided to arrive at their destination at 9 a.m., so how many kilometers per hour?
1. A marching column moves at the speed of 9 km / h, and the correspondent at the end of the column rushes to the front of the column at the speed of 15 km / h to send a letter, and then immediately returns to the end of the column to find the length of the column
2. Party A and Party B set out from two places 80km apart by bicycle at the same time. After two hours, they met each other. It is known that Party A walks 2.4km more than Party B every hour. How many kilometers does Party A and Party B walk per hour
3. A train moves forward at a constant speed. It takes 20 seconds from entering the 300 m long tunnel to leaving the tunnel completely. A fixed spotlight on the top of the tunnel shines on the train for 10 seconds. How long is the train's body?

1. Suppose that the distance between Party A and Party B is x km (x △ 2.5) - (x △ 3) = 2x = 30. 2. Suppose that the distance between Party A and Party B is y km 7.5 × (10-8) = (9-8) YY = 15. 1. Suppose that the length of the team is x / (15-9) + X / (15 + 9) = 1 / 3, x + X / 4 = 2, 5x = 8, x = 1.62

The solution of the equation (2k-1) 3 = (kx-1) 2 is the same as that of 2x-1 = 5-x
Note: for the fraction line, the numerator is in front of, that is, the numerator is in brackets, and the denominator is after

∵ 2x-1=5-x
∴ x=2
Substituting x = 2 into (2k-1) / 3 = (kx-1) / 2
That is, (2k-1) / 3 = (2k-1) / 2
4k-2=6k-3
k=0.5

x-3/2+2x-4/2+3x-5/4+...+8x-10/9=3x-1/2+4x-2/3+...+10x-8/9

（-2x-2)/2+（-2x-2)/3+（-2x-2)/4+… +（-2x-2)/9=0
（-2x-2)*（1/2+1/3+1/4+1/5+… +1/9)=0
-2x-2=0
-2x=2
x=-1

A, B, C three people, a walk 60 meters per minute, B walk 67.5 meters per minute, C walk 75 meters per minute, if a and B two people in the East Village, C in the West Village, the three of them at the same time from the two villages facing each other, C meet B, continue to walk 1 minute to meet A. question: how many meters between the East and west villages?

In one minute, a walks 60 meters and C walks 75 meters, which adds up to 135 meters. This is the distance that B falls from a when B and C meet. Dividing by the distance that B falls from a every minute by 7.5 meters, we get 18 minutes. That is to say, B and C walk in opposite directions and meet in 18 minutes. Multiply the sum of B and C's speeds by 18 minutes to get (67.5 + 75) * 18 = 2565 (meters)

A. B, C, D, e five people went to the store to buy things, each of them spent the whole yuan, they spent a total of 56 yuan. The difference between a and B (that is, the absolute value of the difference between the two people's spending, the same below) is 19 yuan, B, C the difference is 7 yuan, C, d the difference is 5 yuan, D, e the difference is 4 yuan, e, a the difference is 11 yuan. How many yuan did e spend? Why?

Because the sum of the differences should be 0, and in fact the absolute value of the difference is 19 + 7 + 5 + 4 + 11 = 46, that is, it should be the sum of the absolute value 23 of the positive value and the absolute value 23 of the negative value, so the difference between a and B and the difference between D and E are consistent. If the other three differences are negative, we can calculate: a = B + 19 = C + 12 = D + 7 = e + 11, and a + B

If you connect a cuboid with a plane, can the section be a parallelogram
Given the line segment AB, extend AB to C so that BC = AB and D is the midpoint of AC. if DC = 4 cm, calculate the length of ab

+_ +Students, the range of parallelogram can be wide ~! What square, rectangle (rectangle), diamond are parallelogram, so understand?
Flat cut to get a rectangle, yes!
It's a rectangle. It's a rectangle!
There are still many cutting methods, you can try again!
In short, the section may be parallelogram!
Got it?!
You're welcome!
+_ +Your B and D points coincide!

A difficult math problem in junior high school
"The question of the reciprocal" in Baidu Encyclopedia "the reciprocal" -- "the geometric demonstration of the reciprocal of 1 and 0"
http://baike.baidu.com/view/294349.htm#6 (turning down)
As shown in the figure, the top of the number axis is tangent to the unit circle P, and the intersection point is the origin o
Each point on the number axis can correspond to the corresponding tangent point on the single circle P, which is called projection. The projection of X on the unit circle is a
Let's look at the tangent B of the reciprocal 1 / X of X on the circle P, connecting ab
It can be proved that AB is perpendicular to the number axis
I don't lack wealth value, everyone help!

Two methods, geometric proof: let the point of X be D, the point of 1 / X be e, connect PD, PE, and record the intersection of AD and be as F, because OP = 1, OD = x, OE = 1 / x, so op / OD = OE / op, and because ∠ pod = ∠ Poe = 90 °, so △ Poe ∽ DOP, so ∠ ope = ∠ PDO, because ∠ OPB = 2 ∠ ope ∠ ODA = 2 ∠ PDO