Limx approaches infinity (Xe ^ X / 2) / (x + e ^ x)

(xe^x/2)/（x+e^x）＝1/[1/e^(x/2) +e^(x/2)/x]
When x tends to infinity, 1 / e ^ (x / 2) tends to zero, e ^ (x / 2) / X tends to infinity, so 1 / [1 / e ^ (x / 2) + e ^ (x / 2) / x] tends to zero

Find limx tends to 0 [5x ^ 2-2 (1-cos2x)] / (3x ^ 3 + 4tanx ^ 2) limit

The numerator and denominator are divided by X & # 178;,
Original limit = Lim [x → 0] [5-2 (1-cos2x) / X & # 178;] / (3x + 4tanx & # 178; / X & # 178;)
Every limit can be worked out
=(5-4)/(0+4)
=1/4
Where: lim2 (1-cos2x) / X & # 178; = lim2 (1 / 2) (2x) &# 178; / X & # 178; = 4
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The railway between Party A and Party B is 480 km long. Passenger cars and freight cars leave each other at the same time. After four hours of meeting, it is known that freight cars travel 65 km per hour
How many kilometers does the truck travel per hour

480÷4-65
=120-65
=55 (km)
A: trucks travel 55 kilometers per hour
Set up freight cars to travel x kilometers per hour
65+x=480÷4
65+x=120
x=55

How to compare the square of a equals 2 and the cube of B equals 3

Because the square of a is equal to 2, the cube of a is equal to 2, the cube of B is equal to 3, the square of B is equal to 9. Because the sixth power of a is less than the sixth power of B, a is less than B

How does 7 in 3 (x + 2.5) = 5x 3x + 7 = 5x 7 = 5x-3x 2x = 7 x = 3.5 come from

3（x+2.5）=5x
3x+7.5=5x
7.5=2x
x=3.25

For a 2-meter-long cylindrical wood, after cutting off a 2-decimeter-long cylindrical block, the surface area is reduced by 12.56 square decimeters. What is the volume of the original wood?

The bottom radius of the cylinder: 12.56 △ 2 △ 3.14 △ 2, = 12.56 △ 2 (2 × 3.14 × 2), = 12.56 △ 12.56, = 1 (decimeter); the volume of the steel: 2m = 20 decimeter, 3.14 × 12 × 20, = 3.14 × 1 × 20, = 62.8 (square decimeter); answer: the original volume of the steel is 62.8 cubic decimeter

1 / 3 of a number is exactly equal to the product of 5 / 9 and 2.75. What is the number?

5/9*11/4*3=55/12

I don't know how to start this kind of problem. Because of the time limit, I can't understand it deeply
Fortunately, the test is not very difficult. It's just about understanding the formula and simple changes,
I hope you can give me a patient answer, the best formula and so on
Can do change a number also can solve go!
The minimum positive period of the function y = 1 + SiNx / 3 is:
Is the so-called minimum positive period + 360? Or should we look at it in combination with the original graph of sin?
The meaning is the same, that is, a little change~
If the minimum positive period of the function y = sin α x times cos α x (α > 0) is 4 π, then the constant α =?
3 when the function y = 2Sin (3x + π / 6) reaches the maximum, x =?
I don't know if these three questions are of the same type

1、2π/(1/3)=6π
2. Y = 1 / 2 (sin (2 α x) t = 2 π / 2 α = 4 π, so a = 1 / 4
3. When the maximum value is obtained, 3x + π / 6 = π / 2 + 2K π, so x = π / 9 + 2 / 3K π
This topic uses the same principle, that is, the period is 2 π divided by the coefficient. The second question has sin and COS, so it's best to turn it into a function name, which is easy to calculate. The maximum and minimum value are very easy, and it's easy to master the change trend of sine or cosine and the point at which to get the maximum value

The final scores of class 8 (1) in a school are: 3 students with 100 marks, 13 students with 90 marks, 17 students with 80 marks, 12 students with 70 marks, 2 students with 60 marks, and 3 students with 50 marks. The average score of the whole class in mathematics examination is______ (the result is kept to one place)

According to the meaning of the question: (100 × 3 + 90 × 13 + 80 × 17 + 70 × 12 + 60 × 2 + 50 × 3) / (3 + 13 + 17 + 12 + 2 + 3) = 3940 △ 50 ≈ 79 (points)

Limx approaches infinity (Xe ^ X / 2) / (x + e ^ x)