Bookstores bring in a kind of books, which sell 30% in the first day, and 120% in the second day. The second day sells 30 more than the first day. How many books do bookstores bring in? Step 1: 30% X120% = 36% Step 2: 36% - 30% = 6% Step 3: 30 △ 6% = 500 I just want to ask, the answer to this question is in the last step, why is it 30 ／ 6% instead of 6% ／ 30?

Bookstores bring in a kind of books, which sell 30% in the first day, and 120% in the second day. The second day sells 30 more than the first day. How many books do bookstores bring in? Step 1: 30% X120% = 36% Step 2: 36% - 30% = 6% Step 3: 30 △ 6% = 500 I just want to ask, the answer to this question is in the last step, why is it 30 ／ 6% instead of 6% ／ 30?

The next day more than 30 copies were sold, which was 6% of the total. Of course, 30 divided by 6%

Bookstores bring in a batch of storybooks, which sell 10% of the total on the first day, and 150% of the total on the second day, 25 more than the first day. How many of these storybooks are there?

The next day it was all sold
10％×150％＝15％
The next day sold more than the first
15％－10％＝5％
There are many storybooks
25 △ 5% = 500

Given that a, B and C are three sides of triangle ABC, the equation a [1-x] with respect to x, if the equation a (1-x) ^ 2 + C (1 + x) ^ 2 = 2bx with respect to x, try to judge the triangle ABC with three sides

If the isosceles triangle is reduced to: (a + C) x ^ 2-2 (a + b) x + (a + C) = 0, then △ = [2 (a + b)] ^ 2-4 (a + C) ^ 2 = 0, the solution is: (a + b) ^ 2 = (a + C) ^ 2 | a + B | = | a + C | only b = C isosceles triangle

Given a zero point of F (x) x0 ∈ (2,3), when we use dichotomy to find the approximate value of x0 with accuracy of 0.01,
The sign of judging the function value at the midpoint of each interval needs to be at most_________ Times

Humor
The accuracy is as follows
(3-2)/2^n
To be accurate to 0.01, the above formula is less than or equal to 0.01, and the solution N = 7

Linear algebra homogeneous linear equations in the free unknown how to determine, you adults give an effective method

In this paper, the coefficient matrix is transformed into a ladder matrix by elementary row transformation. The first non-zero element of a non-zero row is 1,6,9, which is located in 1,3,5 columns, x1, X3, X5

|-3-1 | - 5x (- 4) - 0.5 divided by 0.2 =?

|-3-1 | - 5x (- 4) - 0.5 divided by 0.2
=|-3-1|-5×(-4)²-0.5÷0.2
=4-80-2.5
=-78.5

Given a = {x | x ＜ - 1 or X ＞ 2}, B = {x | 4x + a ＜ 0}, when B ⊆ a, the value range of real number a is obtained

∵ a = {x | x ＜ - 1 or X ＞ 2}, B = {x | 4x + a ＜ 0} = {x | x ＜ - A4}, ∵ a ⊇ B, ｜ - A4 ≤ - 1, that is, a ≥ 4, so the value range of a is a ≥ 4

When x = negative 5, the value of the square of the algebraic formula x + mx-10 is 0, and the value of M?

When x = negative 5, the square of the algebraic expression x + mx-10 is 0
(-5)^2+m (-5)-10=0
25-5m-10=0
5m=15
m=3

Solve the inequality log2 (x ^ 2 + 6x + 1) ≤ 3. Loga (X-2 / x) > 0 (a > 0, a ≠ 1)
There should be a detailed process (2 after log, a is the base)

log2(x^2+6x+1)≤3
=> log2(x^2+6x+1)≤log2(8)
=> x^2+6x+1≤8
=> -7≤x≤1
0 (x-2/x) -1 loga(x-2/x)＞loga(1)
=> (x-2/x)>1
=> x2

If a + C = B, then the equation AX2 + BX + C = 0 (a ≠ 0) must have a root ()
A. 1B. -1C. ±1D. 0

According to the meaning of the question: when x = - 1, the left side of the equation = A-B + C and a + C = B, that is, A-B + C = 0, so when x = - 1, the equation AX2 + BX + C = 0 holds. So x = - 1 is a root of the equation