Integral: upper limit ln8, lower limit Ln3, integral expression √ (1 + e ^ x) DX, that is ∫_ Ln3 ^ ln8 √ (1 + e ^ x) DX, answer 2 + ln3-ln2

Integral: upper limit ln8, lower limit Ln3, integral expression √ (1 + e ^ x) DX, that is ∫_ Ln3 ^ ln8 √ (1 + e ^ x) DX, answer 2 + ln3-ln2

∫ (Ln3 → ln8) √ (1 + e ^ x) DX let u = √ (1 + e ^ x), x = ln (U & # 178; - 1), DX = 2U / (U & # 178; - 1) when x = Ln3, u = 2, when x = ln8, u = 3 = ∫ (2 → 3) U * (2U) / (U & # 178; - 1) Du = 2 ∫ (2 → 3) [(U & # 178; - 1) + 1] / (U & # 178; - 1) du

Calculate the approximate value of ln3.03 by differential equation (take Ln3 = 1.0986)
We need to explain it in detail

LNX Talor expansion, and then into the specific value on the line,

∫(ln3,0)(1/(1+e^-x))dx

∫ (ln3,0) (1 / (1 + e ^ - x)) DX
=∫(ln3,0)(e^x/(1+e^x))dx
=∫(ln3,0)(1/(1+e^x))de^x
=ln(1+e^x)[ln3,0]
I'll do it myself

In the known arithmetic sequence {an}, | A3 | = | A9 |, the tolerance D ＜ 0, if SN is the sum of the first n terms of the sequence {an}, then the size relationship between S5 and S6 is?

Because da9
|a3|=|a9|,
a3>0,a9

On the straight road, a car starts to make uniform acceleration at the speed of 36km / h, and the acceleration is 0.5m/s2. Q: what is the speed of the car after 10s?

Taking the initial velocity direction as the positive direction, the vehicle motion V0 = 36km / h = 10m / s, acceleration a = 0.5m/s2. According to the speed time relationship, the vehicle speed after 10s is v = V0 + at = 10 + 0.5 × 10m / S = 15m / s. A: the vehicle speed after 10s is 15m / s

Xiao Gang of the school track and field team ran most of the distance at an average speed of 6 m / s in the 400 m running test, and finally finished the test at a speed of 6 m / s
8 meters / second speed sprint to the end, the result is 1 minute and 5 seconds. How much time did Xiao Gang spend in the sprint stage?

Five seconds
Suppose xiao gang ran x seconds in the sprint stage, and before that, he ran (65-x) seconds at the speed of 6 m / s
Then 8x + 6 (65-x) is equal to the total distance of 400 meters, and x = 5 seconds

(1) In the June calendar of a certain year, draw a circle arbitrarily to circle three adjacent numbers on a vertical column. If the middle one is a, then the algebraic expression containing a indicates that the three numbers (from small to large) are_______ .
(2) In figure (2), is it possible to make the sum of nine numbers in a square frame equal to 2004 and 2007? If it is possible to find these 16 numbers, if not, give the reason
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31 32 33 34 35
36 37 38 39 40 41 42
……
1996 1997 1998 1999 2000 2001 2002
2003 2004 2005 2006 2007
Figure 2
10. 11, 12, 17, 18, 19, 24, 25, 26 are framed

1,a-7,a,a+7

AB two points, on the number axis, point a corresponds to 2, line AB length is 3, then point B corresponds to the number of?

Let the number corresponding to point B be x, then | X-2 | = 3,
So X-2 = 3 or X-2 = - 3,
So x = 5 or x = - 1,
That is, the number represented by point B is 5 or - 1
Are you satisfied with the above answers?

As shown in the figure, to measure the distance between two points a and B on the opposite bank of the river, take point C in the direction perpendicular to AB, and measure AC = a, angle ACB = α, then AB =?

tagα=a/AB
AB=tagα*a

Comprehensive training of addition and subtraction of integral
1. In the following groups, the items that are not of the same category are ()
A 0.5A & # 178; B and 3AB & # 178; B 2x & # 178; y and - 2x & # 178; Y C 5 and 1 / 3 D - 2XM and - 3xm (M is small)
2. If one of the seven consecutive integers is n, then the sum of the seven integers is ()
A 0 B 7n C - 7n D cannot be determined
3. If 3a and 2A + 5 are opposite numbers, then a is equal to ()
A 5 B -2 C 1 D -5
4. There are () a, B, C, D and four errors in the following bracket removal
①a+(b+c)=ab+c ②a-（b+c-d）=a-b-c+d ③a+2（b-c）=a+2b-c ④a²-[-（-a+b）]-a²-a+b=a²-a+b
5. Calculation: m - [n-2m - (m-n)] equals ()
A -2n B 2m C 4m-2n D2n-2m
6. The difference between formula 3A & # 178; - B & # 178; and a & # 178; + B & # 178; is ()
A 2a² B 2a²-2b² C 4a² D 4a²-2b²
7. The opposite number of - A + B-C is ()
A -a-b+c B a-b+c C -a-b+c D -a-b-c
8. Subtracting - 3M equals 5m & # 178; - 3m-5 is ()
A 5（m²-1） B 5m²-6m-5 C 5（m²+1） D -（5m²+6m-5）
Fill in the blanks:
1. If 3A & # 178; BN and 4amb are of the same kind (N and m are small), then M = () n = ()
2. In 7x & # 178; - 4x + 1-x & # 178; - 2 + 6x, 7x & # 178; is similar to (), 6x and () are similar, and - 2 and () are similar
3. The sum of monomials 3A & # 178; B, 2Ab, - 3AB & # 178;, - 4A & # 178; B, 3AB is ()
4. Arrange the polynomials 5xy-3x & # 179; Y & # 178; - 5 + X & # 178; Y & # 179; according to the exponent of the letter X from large to small
5. If (A & # 178; - 3a-1) + a = A & # 178; - A + 4, then a = ()
6. Simplification: 7x-5x = () 2 / 1a-3 / 1A + 6 / 5A = () - 7a & # 178; B + 7ba & # 178; = ()
7. Remove brackets: - x + 2 (Y-2) = () 2a-3 (B + C-D) = ()
8. It is known that a-c = 2, B-C = 3, then a + b-2c = ()

If one of the seven consecutive integers is n, then the sum of the seven integers is (b) 3. If 3a and 2A + 5 are opposite to each other, then a is equal to () 4. The following common (b) 5. Calculation: m - [n -...]