∫ y ^ 2 * e ^ - YDY = how to calculate

∫ y ^ 2 * e ^ - YDY = how to calculate

Original formula = - Y & # 178; e ^ (- y) + 2 ∫ Ye ^ (- y) dy
=-Y & # 178; e ^ (- y) - 2ye ^ (- y) + 2 ∫ e ^ (- y) dy
=-Y & # 178; e ^ (- y) - 2ye ^ (- y) - 2E ^ (- y) + C (C is any constant)
=C-(y²+2y+2)e^(-y).

(e ^ Y-1) e ^ xdx + (e ^ x + 1) e ^ YDY = 0. 3Q

Because e ^ xdx = D (e ^ x); e ^ YDY = D (e ^ y), so (e ^ Y-1) e ^ xdx + (e ^ x + 1) e ^ YDY = 0 (e ^ Y-1) d (e ^ x) + (e ^ x + 1) D (e ^ y) = 0 (e ^ x + 1) d (e ^ y) = - (e ^ Y-1) d (e ^ x) (separate variable) d (e ^ y) / (e ^ Y-1) = - D (e ^ x) / (e ^ x + 1), then ln (e ^ Y-1) = ln [1 / (e ^ x + 1)] + C (C is constant)

There are 18 boys in class 6 (5), 2 / 3 of girls. How many girls are there in class 6 (5)

There are x girls
X*2/3=18
X=18*3/2
X=27
There are 27 girls in class 6 (5)

On the polynomial 6mxx + 4nxy + 2x + 2XY XX + y + 4 of XY without quadratic term, find the value of 6m-2n + 2

Original formula = (6m-1) XX + (4N + 2) XY + 2x + y + 4
The first two are quadratic terms
So their coefficient is zero
So 6m-1 = 0
4n+2=0
So 6m = 1, 2n = - 1
So 6m-2n + 2 = 0 + 1 + 2 = 3

I read one sixth of a story book on the first day and 24 pages on the second day,
The third day is 150% of the total number of the previous two days. There is still a quarter left. How many pages must be read before three o'clock this afternoon

It's very simple
Let the total number of pages be X
Lie equation
1 / 6 * x + 24 + (1 / 6 * x + 24) × 150% + 1 / 4 * x = x
The solution of the equation is x = 16

When Wang Ming calculates the difference between a polynomial minus the square of 2B + B-5, he forgot to enclose the two polynomials in brackets, so the two terms after the subtraction do not change sign, and the result is 2B + 3b-1. Based on this, can you work out the polynomial? Can you work out the correct result?

A truck and a car drive from a to B at the same time. The car returns immediately after arriving at B, and the speed increases by 50%. Two hours after departure, the car and the truck meet for the first time. When the truck arrives at B, the car just goes to the midpoint of a and B. how long does it take for the car to go back and forth between a and B?

Let the speed of the car go to x, then the speed of the car return is: (1 + 50%) x = 32x, the time for the truck to complete the whole journey is: 1x + 12 △ 32x = 43x (hours), the speed of the truck is: 1 △ 43x = 34x, the distance for two cars to meet and walk together is the whole journey: 1-34 = 14

The five general steps of drawing the number axis
Please see that there are five~

I think it should be (1) draw a straight line
(2) Set the origin
(3) Measure the length of the partition
(4) Place a number under the corresponding position
(5) Mark the positive direction
The above is purely personal speculation

It takes 8 hours for a bus to drive from city a to city B, and 12 hours for a truck to drive from city B to city A. the two cars drive from the two cities at the same time, and the bus runs 264 kilometers when they meet. What is the distance between city a and city B?

Definition: A is a rational number which is not equal to 1. We call 1-A the difference reciprocal of A. for example, the difference reciprocal of 2 is 1-2
Definition: A is a rational number which is not equal to 1
one
1-a
It is called the reciprocal of the difference of A
one
1-2
=-What is the reciprocal of the difference between 1 and - 1
one
1-(-1)
=
one
two
. A1 is known=-
one
five
A 2 is the difference reciprocal of a 1, a 3 is the difference reciprocal of a 2, a 4 is the difference reciprocal of a 3, and so on, then a 10 =?

a10=a1=-1/5