In the extra-curricular books, the sentences describing the actions, expressions, language and psychological appearance are very complex, and the number of words in each aspect is about 15 I'll give you one

In the extra-curricular books, the sentences describing the actions, expressions, language and psychological appearance are very complex, and the number of words in each aspect is about 15 I'll give you one

Look: my deskmate is very competitive. A few days ago, he got 98 points in the Chinese test. What about him? 97 points. Just one point away, he was not happy. He took the test paper with his mouth in his mouth and looked at it carefully Just wondering, he burst out laughing as if he had found a new world

To print a manuscript, if 2400 words are printed per hour, it can be completed in 8 hours. If it is required to be completed in 6 hours, how many more words must be printed per hour?
To solve by proportion

Because the total number of words is constant, the number of words printed per hour is inversely proportional to the time
Set the number of X words to be printed every hour
6×（2400+x）=2400×8
14400+6x=19200
6x=19200-14400
6x=4800
x=800
A: you have to print 800 more words per hour

Judge the triangle shape with three lower points a (1, - 1) B (2,1) C (- 1, - 1) as vertices

ab=√[(2-1)²+(1+1)²]=√5
ac=1-(-1)=2
bc=√[(2+1)²+(1+1)²]=√13
So BC & # 178; > AB & # 178; + AC & # 178;
So it's an obtuse triangle

If the real number T satisfies f (T) = - t, then t is said to be a secondary fixed point of the function f (x). Let f (x) = LNX and the sum of all secondary fixed points of the inverse function be m, then M=______ ．

The inverse function of the function y = LNX: y = ex; the image of the function y = LNX and the line y = - X have a unique common point (T, - t), then t = - ln (- t), and ex = - x ⇔ x = ln (- x) ⇔ x = - T. so the sum of all secondary fixed points of the two functions M = t + (- t) = 0, so the answer is 0

2 to math problem (writing process) write good bonus points
1. Cut a cube whose edge length is a centimeter into two equal cuboids. The sum of the surface area of the two cuboids is () square centimeter more than that of the original cube
2. A rectangular reservoir can store 360 cubic meters of water at most. Given that the water depth of the reservoir is 5 meters, how many square meters does it cover?

1. The surface area of the cube with the edge length of a CM is 6A square cm, and the area of a single cuboid cut into small cuboids is 2A + 4 * (1 / 2a) = 4A. The total area of the two cuboids is 8A square cm
2. Rectangle volume = bottom area * height
The floor area is both bottom and high
360/5=72
The answer is to cover an area of 72 square meters

Derivative of y = SiNx ^ 2-sin3x
topic
I don't understand. Can you be more specific,
But my answer is 2cosxsinx-3sosx
I still don't understand why it's sin2x. The title is SiNx ^ 2
But it's SiNx ^ 2
y=u^2,u=sinx
2u*cosx
=2sinxcosx

That's right. I just want to say that the square of SiNx should be written as sin ^ 2 (x)

Mathematics problems in large class of kindergarten
Little mice love to eat sugar. They ate more than half of the total on the first day. On the second day, they ate more than half of the rest. On the third day, what was the total number of the remaining three pieces of sugar?
How did you figure it out?

Kindergarten At the beginning, I wanted to make an equation. Look, it's Kindergarten No more Ha ha. The next day, I ate more than half of the remaining one. Use my brain. You think, the last three pieces are left. Isn't the rest 3 + 1 = 4 fast? Then half of the whole sugar is 8, and so on, 8 + 1 = 9, 9 × 2 = 18

Xiao Hong and Xiao Xin solve the equations ax + 5Y = 13 & nbsp; & amp; (1) 4x − by = − 2 & nbsp; & amp; (2) Xiaohong read a wrong way while doing homework and watching TV, and got the solution of the equations as x = − 3Y = − 1; Xiaoxin read B wrong while doing homework and eating snacks, and got the solution of the equations as x = 5Y = 4?

Because Xiaohong only misread a in equation (1), the solution obtained by Xiaohong should satisfy the equation (2) without a, that is, 4 × (- 3) - B × (- 1) = - 2 & nbsp; (3). Similarly, the solution obtained by Xiaoxin should satisfy the equation (1) without B, that is, a × 5 + 5 × 4 = 13 & nbsp; (4) from (3) and (4), a = - 75B

1. Now there are chickens and rabbits in the same cage, with 35 heads on the top and 94 feet on the bottom. How many chickens and rabbits are there?
2. There are 25 birds on the two trees, five of them fly from the first tree to the second tree, and seven of them fly away from the second tree. At this time, the number of birds on the first tree is twice that on the second tree. How many birds are there on each tree?

1. Suppose 35 are all rabbits
35 * 4 = 140
140-94 = 46
4-2 = 2
Chicken: 46 / 2 = 23
Rabbits: 35-23 = 12
A: there are 23 chickens and 12 rabbits
2.25-7 = 18
Now the second tree: 18 / 3 = 6
Now the first tree: 6 * 2 = 12
Original first tree: 12 + 5 = 17
Original second tree: 25-17 = 8
A: there were 17 birds in the first tree and 8 birds in the second tree
A bird

It is known that the line y = KX + B and the line y = 2x + 8 intersect at the same point on the x-axis, and the area enclosed by the line y = KX + B and the coordinate axis is 4,
Finding the analytic formula of y = KX + B

The line y = 2x + 8 intersects a point (- 4,0) on the x-axis
s=1/2*4*b=4
B = 2 or - 2
Straight line y = KX + B over (0,2) (- 4,0) y = 1 / 2x + 2
Or the line y = KX + B passes (0, - 2) (- 4,0) y = - 1 / 2x-2