The number of boys in a three-year class is 4 less than 5 / 9 of the whole class. The number of girls in a three-year class is 6 more than 2 / 5 There are six more girls than two fifths of the class

The number of boys in a three-year class is 4 less than 5 / 9 of the whole class. The number of girls in a three-year class is 6 more than 2 / 5 There are six more girls than two fifths of the class

Boys are 4 less than 5 / 9 of the class
There are four more girls than 1-5 / 9 = 4 / 9 in the class
It is also known that there are six more girls than two fifths of the class
There are: (6-4) / (4 / 9-2 / 5) = 2 / 2 / 45 = 45 students in the class

The ratio of boys to girls in class 6 (1) is 4:3. Girls are 8 less than boys. How many students are there in the class?

The students in class 6 [1] are divided into 4 + 3 = 7 shares. Boys use 4-3 = 1 share more than girls. Each share is 8 ／ 1 = 8, and 8x7 = 56. There are 56 students in the whole class

The ratio of boys to girls in class 6 (3) is 5:3. Girls account for ()% of the class, and girls are () less than boys

The ratio of boys to girls in class 6 (3) is 5:3. Girls account for (37.5)%, and girls are (40)%
If you don't understand this question, you can ask,

36 * 72. When 2 * 3 = 6 is calculated in the vertical formula, 6 means () in the vertical formula ()

36 * 72, when 2 * 3 = 6 in the vertical calculation, 6 means (2) (30) in the vertical calculation

Lim x tends to 0 x-arcsinx / (arcsinx) ^ 3, why can't it be equivalent to ((1 / 6) x ^ 3) / x ^ 3
Is x-arcsinx equivalent to 1 / 6 x ^ 3

Let u = arcsinx,
Then x-arcsinx = sinu-u
We can prove sinu-u ～ - (1 / 6) U & # 179; - (1 / 6) x & # 179 by using the law of lobita;
Therefore, x-arcsinx is equivalent to - (1 / 6) x & # 179;

4x-3y = 7, 4x + 2Y = 2, solve the binary linear equation

4x-3y=7,①
4x+2y=2②
① - 2
-3y-2y=7-2
-5y=5
y=-1
Substituting (1)
4x+3=7
4x=4
x=1
So the solution of the original equation is x = 1
y=-1

If the sum of the first four terms of an arithmetic sequence is 40, the sum of the last four terms is 80, and the sum of all terms is 210, then the sequence has ()
A. 12 items B. 14 items C. 16 items D. 18 items

According to the properties of arithmetic sequence, the sum of the first term and the last term is a1 + an = 40 + 804 = 30. According to the sum of all terms is 210 = (a1 + an) · N2, the solution is n = 14, so B

Let f (x) = llgxl, if 0

F (x) = | lgx | = lgx (when x > = 1)
=-Lgx (when 0f (b),),
This situation is in line with the meaning of the question

On the expression of physical power P in grade three
The more, the better. Thank you very much if it's really useful

Electrical part, such as w = uit (W: electrical work, I: current, u: voltage, t: time)
P = w / T P = IU P = u × U / r = I * I * r = q (heat) / T q = Pt r = u × U / P I = P / u
(* means ×)
P = w / T, w = FS, P = Fv (P = w / T = FS / T = FV) η = w / W total × 100% (mechanical efficiency)
P = mg = V ρ g = sh ρ g (volume of water column v = sh, density of water ρ, mass of water column m = V ρ) the pressure of water column on its bottom is p = f / S = sh ρ g / S = ρ Hg, which is all I know,

The total capacity of the Three Gorges Reservoir on the Yangtze River is about three times that of the Xiaolangdi Reservoir on the Yellow River. The total capacity of the Xiaolangdi Reservoir on the Yellow River is 26 billion cubic meters less than that of the Three Gorges Reservoir on the Yangtze River

Taking Xiaolangdi Reservoir as a multiple
So the capacity of Xiaolangdi reservoir is 260 / (3-1) = 13 billion cubic meters
Three Gorges: 130 + 260 = 39 billion cubic meters