There are two kinds of books in the school library. There are 60 more science and technology books than story books. The number of story books is 85% of science and technology books. How many science and technology books and story books do you buy?

A: there are 400 science and technology books and 340 story books

There are 10000 science and technology books and story books in the school library. The ratio of science and technology books to story books is 3:2. How many more science and technology books are there than story books

If it is an equation:
Let the science book be 3x and the story book be 2x
3x+2x=10000
x=2000
Science and technology book 3x = 6000
Storybook 2x = 4000
In case of calculation:
Science and technology book 10000 ÷ (3 + 2) × 3 = 6000
Storybook 10000 ÷ (3 + 2) × 2 = 4000
A: 6000 science and technology books and 4000 story books

If LG2, LG (2x-1), LG (2x + 3) are in arithmetic sequence, then the value of X is equal to______ ．

∵ LG2, LG (2x-1), LG (2x + 3) are in arithmetic sequence, ∵ 2lg (2x-1) = LG2 + LG (2x + 3), ∵ LG (2x-1) 2 = LG (2x + 1 + 6), which is reduced to (2x-1) 2 = 2x + 1 + 6 and sorted into (2x) 2-4 × 2x-5 = 0, that is, (2x-5) (2x + 1) = 0, (*) ∵ 2x > 0, ∵ 2x + 1 > 1, ∵ (*)

I was preparing my birthday present today last year?

Last year today I am preparing for a birthday present
I don't know if this is up to your standard

How many Mu is the land 150 meters long and 100 meters wide?

1 mu = 666.6 square meters, you have 15000 square meters, about 22.5 mu

Given the point a (2,2) B (5,3) C (3, - 1), if XY satisfies the circular equation to find the maximum value of x square + y square and x-2y, the key is the latter question!

The coordinates of these three points can be substituted into the general formula of a circle
(x-a) ^ 2 + (y-b) ^ 2 = R ^ 2. After solving these equations, we can get a = 4, B = 1, R ^ 2 = 5
(x-4) ^ 2 + (Y-1) ^ 2 = 5, y = 1 + radical [5 - (x-4) ^ 2], y = 1 - radical [5 - (x-4) ^ 2]
Let z = x - 2Y and substitute the value of Y (first use the positive root sign value)
=X - 2 {1 + radical [5 - (x-4) ^ 2]}
Find DZ / DX = 1 - [- 2 (x-4)] / radical [5 - (x-4) ^ 2] [5 - (x-4) ^ 2 is not equal to 0]
Let DZ / DX = 0, let x < 4, then x = 3
Y = 3 or - 1, X - 2Y = - 3 or 5
Then let z = x - 2Y, and substitute the value of Y (with the value of negative root sign)
=X - 2 {1 - radical [5 - (x-4) ^ 2]}
Find DZ / DX = 1 + [- 2 (x-4)] / radical [5 - (x-4) ^ 2] [5 - (x-4) ^ 2 is not equal to 0]
Let DZ / DX = 0, let x > 4, then x = 5
Y = 3 or - 1, X - 2Y = - 1 or 7
When 5 - (x-4) ^ 2 equals 0, y = 1, x = 1.76 or 6.24, the value of X - 2Y is between - 3 and 7
The maximum value of X - 2Y is 7 and the minimum value is - 3
Using the same method, we can find the maximum and minimum of Z = x ^ 2 + y ^ 2. It's troublesome, so I won't do it. I believe the questioner can handle it. If you have any questions, please ask again

I am healthier than before?

I am healthier than before

How does Miss Liu write in English

Miss Liu

Let u = the square of XY + X, and find the total differential Du | Du | at point (1,0). There is a (1,0) in the lower right corner of this

u = xy + x^2
∂u/∂x = y + 2x
∂u/∂y = x
du = ∂u/∂x dx + ∂u/∂y dy
= (y + 2x)dx + xdy
du (x=1,y=0) = 2dx + dy

A simple calculation method of 158-69 + 42-31

158+42 =200 69+31=100 200-100=?

There are two kinds of books in the school library. There are 60 more science and technology books than story books. The number of story books is 85% of science and technology books. How many science and technology books and story books do you buy?