The school bought 230 new books of three kinds, of which children's books are twice as much as popular science books, and story books are one third of popular science books?

Popular science reading materials: 230 (1 + 2 + 1 / 3) = 69
Children's books: 69 × 2 = 138
Storybooks: 69 × 1 / 3 = 23

What are the examples of comic books, composition books, children's books, story books, ancient poetry books, ancient prose, philosophy and ethics, national myths, history and humanities, art and literature

The school has 320 popular science books, accounting for 25% of all books, and popular science books are equivalent to 43% of story books. (1) how many books are there in the library? (2) How many story books are there?

(1) 320 △ 25 = 800 (copies); answer: there are 800 books in the library. (2) 320 △ 43 = 240 (copies); answer: there are 240 story books

Least common multiple of 35 and 56
What is it? Come on

The least common multiple of 35 and 56 is 280, because the common factor of 35 and 56 is 7,5 * 7 = 35,7 * 8 = 56, so calculate the number of 5 * 7 * 8, and finally equal to 280, which is their least common multiple. There are also 8 times of 35, 5 times of 56, and 280, which are both OK!

Because the two ratios of 3:4:1 and 4:3:1 are equal to (), the proportion ()

Because the two ratios of 3:4:1 and 4:3:1 are equal to (12), the ratio (3:1 / 4 = 4:1 / 3) can be formed

The following propositions are proved to be false by counter examples
1. The square of any number is greater than 0
2. If AB = 0, then a = 0
3. The difference between two negative numbers is negative
4. The sum of a positive number and a negative number must be positive

The square of 0 equals 0
a=2 b=0 ab=0
-2-（-5）=3
-5+2=-3

It is known that the sum of three positive numbers in the arithmetic sequence is equal to 15, and the three real numbers add 1,1,4 at one time to form an equal proportion sequence. Find the three numbers

Let {an} be equal difference, then a1 + A2 + a3 = 15, so 3 * A2 = 15a2 = 5; and because (a1 + 1) / (A2 + 3) = (A2 + 3) / (A3 + 9), so (A2 + 3) (A2 + 3) = (a1 + 1) (A3 + 9) (a1 + 1) (A3 + 9) = 64a1 + a3 = 10, so, substituting, - A3 * A3 + 2A3 + 35 = 0, the solution is A3 = 7 or A3 = - 5 (rounding)

Given the function f (x) = LG (x2-2x + m), where m ∈ R, and M is a constant. (1) find the domain of the function; & nbsp; (2) can the domain of the function f (x) be a real number set R at the same time? Prove your conclusion. (3) does the image of function f (x) have a symmetry axis parallel to the Y axis? Prove your conclusion

(1) From x2-2x + m > 0, and △ = 4 (1-m) when △ > 0, i.e. m < 1, x > 1 + 1-m or x < 1-1-m when △ = 0, i.e. M = 1, X ≠ 1, when △ 0, i.e. m > 1, X ∈ R, when m > 1, f (x) domain is r, when m = 1, f (x) domain is (- ∞, 1) ∪ (1, + ∞), when m < 1, f (x) domain is (- ∞, 1-1-m) ∪ (1 + 1-m, + ∞) (2) from (1) It is known that in order to make the definition field of function f (x) r, M > 1 is necessary, and in order to make the value field of function f (x) r, Δ = 4-4m ≥ 0, that is & nbsp; If M ≤ 1 is true at the same time, m ＞ 1m ≤ 1 and M has no solution, that is, whether the domain of definition and range of value of F (x) can be a real number set R at the same time. (3) let there be a straight line x = a (a ≠ 0), satisfying that f (x) = f (2a-x), LG (x2-2x + m) = LG [(2a-x) 2-2 (2a-x) + M] and (1-A) (x-a) = 0 ∧ a = 1, so the image of function f (x) has a symmetry axis X = 1 parallel to y axis

It is known that be bisects ∠ ABC, ∠ a = 100 ° to verify: AE + be = BC

Take point F on BC to make BF = be, connect EF, and take point G on BC to make BG = ba,
Because be is the bisector of angle ABC, the angle Abe = angle EBF = 20 ° and be = be, Ba = BG, the triangle Abe is equal to the triangle GBE, so Ge = AE, and the angle Berg = angle bea = 60 ° so the angle EGF = 80 ° and be = BF, so the angle bef = angle BFE = (180 ° - 20 °) / 2 = 80 ° so the angle EGF = angle EFG, so AE = eg = EF, and the angle c = 40 ° so the angle CEF = 80 ° - 40 ° so EF = FC,
In conclusion, AE = eg = EF = FC and BF = be, so AE + be = FC + BF = BC

The number of regularly arranged columns: 2,4,6,8,10,12. Each term can be expressed by formula 2n. The number of regularly arranged columns: 1, - 2
The number of regularly arranged columns: 2,4,6,8,10,12. Each term can be expressed by the formula 2n (n is positive integer). The number of regularly arranged columns: 1, - 2,3, - 4,5, - 6,7, - 8. What formula do you think can be used to express each term?

（-1）^(n+1) × n
-N + 1 power of 1

The school bought 230 new books of three kinds, of which children's books are twice as much as popular science books, and story books are one third of popular science books?