The romance of the Three Kingdoms is one of the four classic Chinese literary works

The romance of the Three Kingdoms is one of the four classic Chinese literary works

The romance of the Three Kingdoms is one of the four classic works in China

Nuwa left a stone when she was refining the stone to fill the sky. It was abandoned under the green ridge peak of the big barren mountain. Later, it was brought into the world by the vast earth and a real person. She experienced all kinds of joys and sorrows

In the first chapter of a dream of Red Mansions, Zhen Shiyin's dream is to understand Jia Yu village's life. The main part is as follows: when Nuwa was refining stones to mend the sky, he made thirty-six thousand five hundred and one pieces of hard stones, twenty-four feet high and twenty-four feet high, on the Wuji cliff of the great barren mountain

High school mathematics, there must be ideas + steps!
Given that X and y satisfy x2 + y2-4 = 0, find the minimum value of y-x

Given that X and y satisfy x2 + y2-4 = 0, find the minimum value of y-x
Because (Y-X) 2 = y2-2xy + x2
y2+x2=(y-x)2+2xy
So x2 + y2-4 = 0
(y-x)2+2xy-4=0
(y-x)2=4-2xy
Y-X = ± 4-2xy under root sign

Given that the opposite number of a is 2 / 3 and the reciprocal of B is - 6 / 5, find the value of a + 3B / a-2b

A is - 2 / 3, B is - 5 / 6, so B / a = 5 / 4, a + 3B / a-2b = - 2 / 3 + 3 * 5 / 4-2 * (- 5 / 6) = 53 / 12

Now we define the operation symbol *, for a given rational number a, B, a, B are not 0. A * b = B power of a, then (- 3) * 2=

(-3)*2=(-3)²=9

What is 0.9 times 100%

100%=1 0.9×100%=0.9=90%

The following equations {2x-5y = 23 3x-10y = 7} are solved by substitution method

{ 2x-5y=23 ①
3x-10y=7②
From (1) to (2)
Y = (2x-23) / 5 is substituted into ② to get
3x-2（2x-23）=7
3x-4x+46=7
x=39
So y = (2 × 39-23) / 5 = 11
Namely
x=39
y=11

There are 2011 people, each one wants a bottle of beverage, 7 empty bottles get one free, how many bottles of beverage do you want to buy

2011x0.8571428571 = 123.71428563 the answer should be 1724!

If x and y satisfy x + 2Y = 3, then the minimum value of 1 / x + 1 / y is?

1/x+1/y
=(1/x+1/y)*3/3
=(1/x+1/y)*(x+2y)/3
=(2y/x+x/y+3)/3
>=(double root 2 + 3) / 3
The equal sign is obtained if and only if 2Y / x = x / y
Simultaneous x + 2Y = 3
The solution is x = 3 times the root sign 2-3
Y = (6-3 times root 2) / 2
In conclusion, the minimum value is (2 times root 2 + 3) / 3
The calculation is not guaranteed to be correct, and there is no problem in thinking
After answering, I wish you happy!

The first group of students went to a fast food restaurant and bought ten hamburgers and French fries. A hamburger cost 10 yuan and a French fries cost 6 yuan. The total cost was 84 yuan. How many hamburgers and French fries did they buy?

Hamburger 6, French fries 4!