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It is known that 3 / x = 5 / y = 7 / Z is not equal to 0. Find the value of the following formula 1. X-Y of y = Z 2.5x-3y + 2x of Z + 3Y + 4Z
From X / 3 = Y / 5 = Z / 7, y = 5x / 3, z = 7x / 3,
（x-y+z)/y=(1-5/3+7/3)/(5/3)=1.
(2x+3y+4z)/(5x-3y+z)=(2+5+28/3)/(5-5+7/3)=7.
Given {x + Z = 5, y + Z = - 2, y + x = 3, then x + y + Z is equal to
Process..
x+z=5 y+z= - 2 y+x=3
Formula 1 + formula 2 + formula 3: x + Z + y + Z + y + x = 5-2 + 3
2(x+y+z)=6
x+y+z=3
When k = x & # 178; - 3kxy-y & # 178; + 2xy-2 and - 2x & # 178; - 3xy + 5 have no XY term
-3kxy+2xy=-3xy
-3k+2=-3
3k=5
k=5/3
Why can forests conserve water and protect soil and water
Most of the forest is composed of woody plants, and their roots are straight roots, that is, the trunk on the ground is turned upside down and then expanded. Such roots can seize the soil and reduce soil erosion. More water is accumulated in the soil to achieve the function of water conservation and water and soil conservation
Of course, the transpiration of plants also accelerates the water cycle of the forest and its surrounding environment, with humid climate and more rainfall, which is also very beneficial to water conservation
Is the difference between at least two of any seven different natural numbers a multiple of 6?
The natural number is divided into six groups according to the remainder of 6, that is {6K}, {6K + 1}, {6K + 2}, {6K + 3}, {6K + 4}, {6K + 5}. Two of any seven natural numbers must belong to the same group, then the remainder of this number divided by 6 is the same, and the difference between them is a multiple of 6
In order to thank customers, mineral water manufacturers have launched a "buy four and get one free" campaign. Originally, each bottle of mineral water costs 0.8 yuan, but now what's the actual discount?
4*0.8/5=0.64
0.64/0.8=0.8
The actual discount was 20%, that is, 20% off
According to my parents' observation, which one is better?
Of course, it's new concept English edited by L.G. Alexander. The young version of the new concept is written by L.G's wife, and the illustrations are ugly. The first three volumes are well arranged, and some of them are fresh. When it comes to the young version 5a, the original text of L.G's new Concept English 2 will appear. Isn't it digging her husband's corner? Or is it that FLTRP just wants to publish books to make money, cheating those ignorant people! So, New concept English volume 1-4 is the classic English self-study textbook!
I hope I can help you!
A. The distance between B and B is 80 kilometers. A bus starts from a to B. two hours later, a car comes from A. the speed of the car is three times that of the bus. As a result, the car arrives at B 40 minutes earlier than the bus
Suppose the speed of the bus is x km / h, then the speed of the car is 3x km / h. The equation is 80x-2-4060 = 803x, and the solution is x = 20. After testing, x = 20 is the solution of the original equation, so 3x = 60. Answer: the speed of the bus is 20 km / h, and the speed of the car is 60 km / h
On the real coefficient equation x2-ax + 2B = 0 of X, if one root is in the interval [0,1] and the other root is in the interval [1,2], then the maximum value of 2A + 3b is______ ．
Let f (x) = x2-ax + 2B, according to the meaning of the problem, the function has one zero point in [0, 1], [1, 2], combined with the image of quadratic function, we know that the condition f (0) ≥ 0f (1) ≤ 0f (2) ≥ 0 {B ≥ 01 − a + 2B ≤ 04 − 2A + 2B ≥ 0 is satisfied, and the feasible region of the point (a, b) satisfying the inequality is made in the rectangular coordinate system. The problem is transformed into determining the optimal solution of the linear objective function: z = 2A + 3B, combined with the graph When the linear objective function: z = 2A + 3b is located at the point C (3,1), i.e. a = 3, B = 1, the maximum value of the objective function is 9
A. The distance between B and B is 950 kilometers. Party A and B start from a to exercise at the same time. Party A walks 40 meters per minute and Party B runs 150 meters per minute for 40 minutes
When we meet face to face, where is the closest and how many meters is the distance?
300 meters from a
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