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Given x > 0, the maximum value of function y = 2-3x-4 / x?
It's too easy, high school student
The square of a plus the square of B is greater than or equal to 2Ab
y=2-（3x+4/x）
X 〉 0 3x is the square of root 3x
The maximum y is 2 minus 2 times the root sign 3
Given that the function y = MX 2 + 43x + NX 2 + 1 has a maximum value of 7 and a minimum value of - 1, find the function
Y (x2 + 1) = MX2 + 43x + N, (Y − m) x2 − 43x + y − n = 0. Obviously, y = m can be established. When y ≠ m, the equation (Y − m) x2 − 43x + y − n = 0 must have a real root, that is, Y2 - (M + n) y + Mn-12 ≤ 0, and - 1 ≤ y ≤ 7 ℅ - 1 and 7 are the equations Y2 - (M + n) y + Mn-12 =
If the area of isosceles △ ABC is 12cm2 and the height of the bottom ad = 3cm, its perimeter is______ cm．
Let the base be a, then 12a · 3 = 12, a = 8, BD = A2 = 4. According to Pythagorean theorem, ab = ad2 + BD2 = 32 + 42 = 5cm, the waist is 5, and the circumference is 5 + 5 + 8 = 18cm
Given that real numbers a and B satisfy a-7a + 2 = 0 and b-7b + 2 = 0, find the value of B / A + A / b
Such as the title
The real numbers a and B satisfy the condition that the square of a-7a + 2 = 0, and the square of b-7b + 2 = 0. It shows that a and B are two parts of the equation x ^ 2-7x + 2 = 0, and a + B = 7, ab = 2, B / A + a / B is divided into (a ^ 2 + B ^ 2) / AB = ((a + b) ^ 2-2ab) / AB = 45 / 2
Between the stars and the moon, I choose the stars! Why?
Bright moon I don't need, I want stars!
Stars accompany you every night, but the moon is not! Key words: accompany! That is to say, you don't like to wake up lonely every day!
Composition on scientific innovation in grade three of primary school
The book of the future
I think you are all familiar with the word "book". However, some students hate books most. For example, do you know what future books are like? At this time, I think you already have a big question mark in your mind. If you know what future books are like, I think your attitude towards books will change dramatically, Let me tell you about the book of the future!
In the future, the function of books will be very big. The appearance is like a mobile phone. It's as thick as paper, but it's much harder than paper. It's even harder than iron. It's all intact. This small machine can make phone calls, listen to songs, surf the Internet and play games. Most importantly, there are all kinds of books in it, which can be compared with ten big galleries
This book can make a phone call, and it can communicate all over the world, which is much better than mobile phone. Another advantage of this book is that it can see what the other party is doing and the face of the other party, so that even if relatives and friends are far away, they can meet every day
This book can also surf the Internet and listen to music, which will give people more entertainment time. When taking a ride, it can also add some fun to the boring journey. If parents are afraid that their children will use it to surf the Internet all day and affect their study, then you are wrong. This machine has the function of telepathy. If someone indulges in it, it will automatically turn off and set a time for you. For example, they can only play five hours a week, Parents do not have to worry, not to mention it can check information, help children learn
Books, of course, focus on reading. There are more than ten big libraries in this machine. There are comic books and books about the subjects that students want to learn. When they go to school, they don't have to carry heavy schoolbags. It makes people more relaxed and it's more convenient to take them when they travel
If there is such a book, then we can certainly spare more time to do other things, which will make human life more convenient. I hope those scientists can really invent such a book, which will certainly stir the world
Cube of (x + 2) + 1 = 0, cube of (x-1) = 8
The cube of (x + 2) + 1 = 0,
Cube of (x + 2) = - 1
Cube of (x + 2) = (- 1)
x+2=-1
x=-3
Cube of (x-1) = 8
Cube of (x-1) = cube of 2
x-1=2
x=3
On a 1:5000 scale drawing, the length and width of the playground of nongnong Nong Street Primary School are 3 cm and 1.2 cm respectively. What is the actual area of the playground
Actual length = 3 * 5000 = 15000 cm = 150 m
Width = 1.2 * 5000 = 6000 cm = 60 m
Actual area = 150 * 60 = 9000 square meters
Mathematician's story in 20 words
Within 20~~~~~
Lewis Carroll, whose real name is Charles letwig Dodgson (1832-1898), is a mathematician. He has been a lecturer in mathematics at Christchurch College of Oxford University for a long time and published several mathematical works. Because of his serious stuttering, he is not good at communicating with people
The geometric meaning of the square of the algebraic formula 4A can be interpreted as
4A the area of a square with a side length of 2A
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