Primary school mathematics application problem: the number a is two fifths more than the number B, so how much is the increase of the number B equal to the number a?

If the number of a is two fifths more than that of B, then B is one, and a is one plus two fifths, which is seven fifths. Seven fifths minus one is two fifths, so B increases by two fifths

What is four fifths by three Sevens divided by four fifths by three Sevens

Nine out of 49

Dongdong has 36 story books. Lili's story book is 5 / 6 of Dongdong's, and Mingming's story book is 4 / 3 of Lili's
Dongdong has 36 storybooks. Lili's is 5 / 6 of Dongdong's and Mingming's is 4 / 3 of Lili's. how many storybooks does Mingming have?
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Mingming 36x5 / 6x4 / 3 = 30x4 / 3 = 40 copies
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For X ∈ R, the values of quadratic function f (x) = x ^ 2-4ax + 2A + 6 (a ∈ R) are all nonnegative. The maximum value of function f (a) = 2-A * | a + 3 | is obtained
For X ∈ R, the values of quadratic function f (x) = x ^ 2-4ax + 2A + 6 (a ∈ R) are all nonnegative numbers, so we can find the function
F (a) = 2-A * | a + 3 |
It's better to have a specific process

F (x) = x ^ 2-4ax + 2A + 6 = x ^ 2-4ax + 4A ^ 2-4a ^ 2 + 2A + 6 = (x-2a) ^ 2-4a ^ 2 + 2A + 6 = (x-2a) ^ 2-2 (a + 1) (2a-3) for X ∈ R, the value of quadratic function f (x) = x ^ 2-4ax + 2A + 6 (a ∈ R) is non negative. When x + 2A = 0, - 2 (a + 1) (2a-3) ≥ 0 (a + 1) (2a-3) ≤ 0-1 ≤ a ≤ 3 / 2F (a) = 2-A * | a + 3

It is known that the root 288A is a positive integer
1. Find the minimum natural number a
2. The largest three digit a
I'm a beginner

Decompose 288 factor, 288 = 12 * 12 * 2
So the minimum natural number is 2
To match 288A with a square number, a is a three digit number
That is to say, a is twice the square of a number
That is, the maximum a is twice the square of 22, that is, a = 968
1.a=2
2.a=968

If the third root of (120a) is an integer, find the minimum positive integer a

If x is the positive integer root of X & # 178; - 2x-2 = 0, find (X & # 178; - 1) / (X & # 178; + x) / [x - (2x-1) / x]

(x \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\1 = √ 3, the original formula = 1 / (...)

If the value of X + 2 / X & # 178; - 2x + 1 is a positive integer, then the value of X is () a.x ＜ - 2 b.x ＜ 1 c.x ＞ - 2 and X ≠ 1 D.X ＞ 1

x+2/x²-2x+1
=(X+2)/(X+1)^2
If the value of X + 2 / X & # 178; - 2x + 1 is positive
(X+2)/(X+1)^2>0
X+2>0
X>-2
At the same time, we should ensure that the denominator (x + 1) ^ 2 is not 0, x + 1 is not 0, X ≠ 1
So: choose c.x ＞ - 2 and X ≠ 1

Given that a > 0, b > 0, M = LG ((a ^ (1 / 2) + B ^ (1 / 2)) / 2, n = LG ((a + b) ^ (1 / 2)) / 2, what is the size relationship between M and N?
There should be a problem-solving process!
This is an exercise about reasoning and proof 2.1.2 deductive reasoning in Chapter 2 of Senior 2

a>0,b>0
(a^(1/2)+b^(1/2))^2=a+b+2(ab)^2>a+b=((a+b)^(1/2))^2
a^(1/2)+b^(1/2) > (a+b)^(1/2)>0
Y = LG (x) is an increasing function in the domain of definition
So LG ((a ^ (1 / 2) + B ^ (1 / 2)) / 2 > LG ((a + b) ^ (1 / 2)) / 2, that is m > n

Let the solution set of inequality l2x-1l < 1 be m 1, and find M 2. If a and B belong to m, try to compare AB + 1 and a + B

（1）|2x-1|

Primary school mathematics application problem: the number a is two fifths more than the number B, so how much is the increase of the number B equal to the number a?