If 3x + 5 = 7, then 3x = 2, according to the properties of the equation_____ On both sides of the equation______ -、 If half x = 10, then x = 20, according to the nature of the equation_____ On both sides of the equation_______ .

If 3x + 5 = 7, then 3x = 2, according to the properties of the equation_____ On both sides of the equation______ -、 If half x = 10, then x = 20, according to the nature of the equation_____ On both sides of the equation_______ .

If 3x + 5 = 7,
If a = B, then a + C = B + C
Add (or subtract) the same integer on both sides of the equation, and the value of the equation remains unchanged
If half x = 10, then x = 20, according to the property of the equation: if a = B, then a × C = B × C
Multiply or divide the same nonzero integer on both sides of the equation, and the value of the equation remains unchanged

4.7 + 3x = 11 use the properties of the equation to solve the equation

4.7+3x=11
4.7+3x-4.7=11-4.7
3X=6.3
3X÷3=6.3÷3
X=2.1

It is known that O is the outer center of the acute angle △ ABC. It is proved that the areas of △ BOC, △ COA and △ AOB form an arithmetic sequence in turn if and only if Tana, tanb and Tanc are arithmetic sequences

First of all, we can prove that in the oblique triangle ABC: Tana + tanb + Tanc = tanatanbtanc syndrome: a + B + C = 180 & # 186; a + B = 180 & # 186; - C, Tan (a + b) = Tan (180 & # 186; - C) = - Tanc [Tana + tanb] / [1-tanatanb] = - tanctana + tanb = - Tanc + tanatanbtanctana + tanb + Tanc = Tana

There was a pile of yellow sand on the construction site, which used 23 tons, just used 60 tons. How many tons of yellow sand was there?

There is a pile of yellow sand on the construction site. Two thirds of it is used, which is just 60 tons. How many tons of yellow sand is there?
60 △ 2 / 3 = 90 tons

The following four propositions: 1. F (x) = 1 is an even function; 2. The image of the function y = f (/ X /) is symmetric about the y-axis

f(x)=1
Then f (- x) = 1
So f (- x) = f (x)
So it's an even function
y=f(|x|)
Then f (| - x |) = f (| - x |)
So y is even, so it's symmetric about the Y axis

A math problem: female workers in a company are 100 / 33 of the total number, 102 less than male workers. How many are male workers? How many are female workers?

If the number of female workers is 100 / 33 of the total number, then the number of male workers is 1-100 / 33 = 100 / 67
102 people, equivalent to 100 / 67-100 / 33 of the total number = 100 / 34
The total number is 102 (100 / 34) = 300
The number of male workers is 300 × 100 / 67 = 201
The number of female workers is 300 × 100 / 33 = 99

Given that circle C: x ^ 2 + y ^ 2-2x + 4y-4 = 0, line L1 passes through point P (2,0), and the chord length cut by circle C is 4 √ 2, the equation of line L1 is obtained

By rewriting the equation of ⊙ C, we get that: (x-1) ^ 2 + (y + 2) ^ 2 = 9. The radius of ⊙ C is 3, and the coordinates of center C are (1, - 2). The chord length of ⊙ L1 cut by ⊙ C is 4 √ 2, and the radius of ⊙ C is 3, but ⊙ L1 is not the center of C

Girls account for four out of seven in class 6 (1), of which two-thirds of boys reach the standard in the physical test. What is the percentage of boys reaching the standard in the whole class?
emergency

Suppose there are 70 students in a class! Four out of seven girls are 40! Thirty boys are 30! Two out of three students reach the standard are 20! Then the answer is two out of seven

Let real numbers x and y satisfy the equation 2x2 + 3y2 = 4x, then the minimum value of X + y is
A. 1 + radical 15 / 2 B, 1-radical 15 / 2 C, 0 d and above are not correct

The solution is 2x2 + 3y2 = 4x
We get 2x2-4x + 3y2 = 0
That is, 2 (x-1) ^ 2 + 3Y ^ 2 = 2
That is, (x-1) ^ 2 + y ^ 2 / (2 / 3) = 1
Therefore, from the trigonometric function knowledge
Let x = 1 + cosa, y = √ 6sina / 3
Then x + y
=1+cosa+√6sina/3
=1+√[1+（√6/3）^2][1/[1+（√6/3）^2]cosa+√6/[1+（√6/3）^2]sina/3]
=1+√15/3sin（a+θ）
≥1-√15/3
This question should be B,
Your answer is wrong

There are 126 students in the fourth grade of Yucai primary school, 32 less than the fifth grade,

There are X students in the fifth grade
2X-32＝126
The solution is x = 79
79 + 126 = 205
That is, there are 205 students in the fourth and fifth grades