Calculation by using definite integral characteristic of periodic function ∫ (upper n π lower 0) | sinx| DX

Calculation by using definite integral characteristic of periodic function ∫ (upper n π lower 0) | sinx| DX


Because this formula is the integral of absolute value, according to the properties of sine function, it is greater than or equal to 0 from 0 to π, so it can be changed into
N * ∫ (upper π lower 0) sinxdx
=N * (- cosx) | (upper π, lower 0)
=2n
That's it!



1. If the integrand is continuous, the indefinite integral must exist. 2. If a bounded function is multiplied by an infinitesimal, it is still an infinitesimal
3. The geometric meaning of indefinite integral is an integral curve
4. The derivative of any infinitesimal is infinitesimal


F (x) = 0 is infinitesimal, so is the derivative



Judgment question: the basic requirement of definite integral is that the integrand domain is finite and the integrand function is bounded. Is it right or wrong?


Correct, if the integrand domain is infinite and the integrand function is unbounded, then it is an abnormal integral



Who can tell me in vernacular what is the positive and negative proportion? It's better to give some examples


A positive proportion is an increase. Another one related to it will increase with it
Inverse proportion is an increase, and the other related to it will decrease
For example, if you put a 2 meter long wooden pole in the sun at the same time, the shadow length will be 3 meters, but if you put a 3 meter long pole in one place, the shadow length will be 5 meters



After the introduction of negative numbers, numbers can be divided into "two kinds of quantities with opposite meanings"?
What are the categories


A: it can be divided into three categories



9. Divide the nine numbers 39, 45, 49, 56, 60, 70, 78, 84 and 91 into three groups so that the product of the three numbers in each group is equal


1.45 56 91
2.60 78 49
3.70 84 39
Because there are three large prime numbers 39, 49 and 91 in the above nine numbers, we can't use decomposition prime number to analyze them
The first step is to analyze the parity of the bits of each number, five even numbers (two zeros, one 6, 8, 4), four odd numbers (one five, two nines, one one). Since five and even numbers can form even numbers, the bits of the product of three numbers are even numbers
In the second step, we know that the number of bits is even, and because there are two zeros, if two zeros are in a group, then the number of bits is zero, another group has five and even number can also be zero, but no matter how the third group is combined, it is impossible to be zero (4, 6, 8, any two can not have zero). Therefore, we can know that 45, 60, 70 are in three groups
In the third step, because the products of the three numbers are equal, 78,84,91 of the remaining 39,49,56,78,84,91 must be different in one group. Similarly, 39,49,56 must not be in the same group. They are composed of six groups: A, 3991 4984 5678; B, 3991 4978 5684; C, 3984 4991 5678; D, 3984 4978 5691; E, 3978 4984 5691; F, 3978 4991 5684, They are combined with 45, 60 and 70 respectively, and 9 and 45 cannot be combined. Otherwise, the number of bits is odd, and the ten bits of them combined with 60 and 70 must be equal. It can be seen that only groups B, D, e and F are possible. There are six combinations of 60 and 9, 70 and 2, or 60 and 6, 70 and 2
a 603991 704978 455684
b 604991 703978 455684
c 603984 704978 455691
d 605691 704978 453984
e 604984 703978 455691
f 605691 703978 454984
From this, we can judge that the number one or three of D is obviously not equal
The rest can only be calculated and confirmed



1000 mu = how many square meters
Conversion of Mu and M2 units
How many square meters is an acre equal to


666.666...*1000=666666.666...



Translation of unit 3a in Grade 9 English volume 1


How do you learn English well? This week we asked students about the best way to learn English in Xinxing high school. Many students said that they have learned English. Some students have more specific suggestions. Lillian Li, for example, the best way to learn new words is to read



Least common multiple of 12 and 14


84



The ratio of 1 / 2 to 1 / 5 is equal to 1 / 4 to X


One in two to one in five equals one in four to X
1/2*x=1/5*1/4
x=(1/20)/(1/2)
x=1/10