Xiao Gang opens another calendar. He finds a number and adds it up with the four numbers above, below, left and right to get 80. He asks Xiao Ming to name the five numbers (solved by linear equation of one variable)

Let this number be x, the first one is X-1, the last one is x + 1, the last one is X-7, the next one is x + 7, all of which add up to 80
x-1+x+1+x+x+7+x-7=80
We get x = 16

Bruce Lee found in the calendar that the sum of the top, bottom, left and right dates of his birthday is 48, then Bruce Lee's birthday is () date

Let's say that the birthday is x, the top and bottom are X-7 and X + 7 respectively, and the left and right are X-1 and X + 1, so the sum is 4x = 48, so x = 12, which is the 12th birthday

On the calendar, the sum of the four dates of grandfather's birthday is 80. Can you tell me when grandfather's birthday is
Make it clear

Hello!
Let the date be X
The top one is X-7, the bottom one is x + 7, the left one is X-1, and the right one is x + 1
So, X-7 + X + 7 + X + 1 + X-1 = 80
X=20
A: on the 20th
Ask me if you don't understand
thank you!

Finding the value of F (4) by the image of exponential function y = f (x) passing through point (2,4)

The expression of all exponential functions can only be y = a ^ X
Over (2,4), that is, a ^ 2 = 4, a = 2
So y = 2 ^ X
So f (4) = 2 ^ 4 = 16

I don't know what I will do next
Change synonymous sentence, urgent········

I don't know what to do next.

On the square root and arithmetic square root of a formula, do not understand
√ a ^ = | a | (the square of root a equals the absolute value of a)
That is, when a is greater than or equal to 0, √ a ^ = a
When a is less than or equal to 0, √ a ^ = - A
I can't understand this
There are two square roots of a number
Then the root sign 25 can be equal to plus or minus 5
How can there be two situations?
Please, everyone!
PS: I don't have many points. I can only offer a reward of 100 points at most. I'll add it at that time!
In addition, I set a = 5
I want to know what those two formulas are about
I'm not asking you the difference between square root and square root...

This sign refers to the square root of arithmetic, so the result is a positive number or 0
That is √ (a ^ 2) > = 0
So if a = 0, it can't be equal to a, because if it's equal to a, it's less than or equal to 0
So we need to be equal to - A, because - A is greater than or equal to 0

How to do this problem about quadratic equation of one variable
）Xuanhua city is known as the "hometown of grapes". There are 100 grape seedlings in a vineyard, with an average yield of 40 kg per plant. Now we are preparing a variety of grape seedlings to improve the yield. However, if there are a variety of grape seedlings, the distance between each plant and the sunlight received by each grape seedling will be reduced. According to practical experience, the relationship between the number of increased plants and the yield of each grape seedling is as follows:
The increased number of plants x (plants)... 10 15 20 22... The yield of each grape seedling y (kg)... 37.5 36.25 35 34.5... (1) please use what you have learned to determine a functional relationship between Y and X;
(2) Under the condition of (1), the functional relationship between the total yield P and X of vineyard was obtained;
(3) Under the condition of (1), when how many more grape seedlings are planted, the total yield of vineyard is the highest?

1. Xuanhua city is known as the "hometown of grapes". There are 100 grape seedlings in a vineyard, with an average yield of 40 kg per plant. Now we are preparing a variety of grape seedlings to improve the yield. However, if there are many kinds of grape seedlings, the distance between each plant and the sunlight received by each grape seedling will be reduced

The summer camp club will build a new swimming pool, which is 50 meters long, twice as wide and 2.5 meters deep. Can you work out the area of the swimming pool?

50x25 = 1250 square meters

The sum of 18 plus 2 / 7 times 7 / 9 is easy to calculate

Ten idioms about horses, one ancient poem

A horse is a horse, a horse is a horse, a horse is a horse, a horse is a horse
The old man in the North lost his horse, his car was dusty, his car was fast, his car was exhausted, his car was tired, his car was slow, his car was tired and his horse died
Try your horse and try your sword
Full of cars and horses, full of cars and horses, boasting and clapping horses and carriages
The east wind and horse's ear fight against the rooster and the horse fight against the horse
To be successful, to be successful, to be successful
A single horse, a white horse, a short horse, two children and one horse
Windmills and horses are not donkeys and horses, windmills and horses don't take the lead, and fire after shooting
Riding on the wind and riding on the horse
A horse in a horse in a horse in a horse in a horse in a bow
A horse with a high head, a horse with a big head, a horse with a big head, a horse with a big head, a horse with a big head, a horse with a big head, a horse with a big head, a horse with a big head, a horse with a big head, a horse with a big head
Hengge Leaping Horse hard work hard work hard work hard work
The black sheep hide the tree and count the horse
a symbol of war in ancient china
Li Shimin
[chanting drinking horses]
Jungu drink Changjing, running and spilling tassels. Fine lines spray together, and the hooves linger in disorder
Water light saddle side, horse shadow slide in the horizontal. Turn like Tianchi, Tengbo dragon species
Jiadao
[send high horse in summer]
In the past 30 years, I have been a guest, and two or three lines of tears suddenly drop down,
The red sun and the red gate are dead. The flowers and hair should delay the new wine, and the grass still writes the poems of the early Dynasty
If you don't want a horse to die in Xizhou, you can draw a horn

Xiao Gang opens another calendar. He finds a number and adds it up with the four numbers above, below, left and right to get 80. He asks Xiao Ming to name the five numbers (solved by linear equation of one variable)