![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
What is the idiom 2345.6789
Lack of clothing [1] eat less [10]
When 1.8 is rewritten as one thousandth unit, it is [] when 1.2345 is rewritten as ten thousand unit. When 1.2345 is rewritten as one thousand unit, it is [] when 1.2345 is rewritten as ten thousand unit
Change 1.8 to one thousandth: 1.800
2. The number of 1.2345 changed into ten thousand units is 0.0012345
The circumference of a rectangle is 72cm. If its width increases by 1 / 4 and its length decreases by 1 / 8, and its circumference remains the same as the original, what is the area of the rectangle?
Let width: A, length: B
a+b=72/2=36
Width increased by 1 / 4, length decreased by 1 / 8, perimeter remained the same as before
a((1+1/4)+b(1-1/8)=a+b
2a=b
a=12,b=24
S=ab=12*24=288
An aircraft first flies at a speed of 200 km / h for a certain distance, and then uses 250 km / h to complete the whole flight,
Cut off points behind Du Niang: the average speed is 215km / h. Seeking the whole journey
An aircraft first flies a distance at a speed of 200 km / h, and then uses 250 km / h to complete the whole flight. It is known that the first distance is 390 km more than the second distance, and the average speed is 215 km / h
Let the first time be T1, the second time be T2, and the whole process be s
V1T1-V2T2=390 200T1-250T2=390 T1=(25T2+39)/20
S / (T1 + T2) = vmean by substituting the above formula into the left formula, we can see that s = vmean * (T1 + T2) = 215 * (20t2 + 25t2 + 39) / 20
At the same time, s = v1t1 + v2t2
It can get 200t1 + 250t2 = 215t1 + 215t2 by juxtaposing with card type
T1=7/3T2
Therefore, it is not necessary to calculate: T2 = 18S, T1 = 42s
S=215*60=12900m
We can get s from the above three formulas
Two people do the same problem: 2x-2 = 4x-4. Huanhuan: 4x-2x = 4-2, that is, 2x = 2. Lele: the inverse operation of the law of distribution of multiplication results in 2 (x-1) = 4 (x-1), and the two sides of the equation divide equally
2 (x-1), get 1 = 2. Lele was shocked at this time, how can 1 equal 2? Can you help him solve the mystery?
(urgent!)
In the equation, X is a variable, and other fixed numbers are constants. To solve the equation, variables should be replaced by constants, so two sides can be divided by two at the same time (x-1), but not divided by variables
In 10 cm long, 8 cm wide rectangular cardboard, dig out the largest circle, the area of this circle is how many square centimeters, the utilization rate of this cardboard?
In 10 cm long, 8 cm wide rectangular cardboard, dig out the largest circle, the diameter of the circle is equal to the width of the rectangle
So the radius of the circle is 8 △ 2 = 4cm
The area is 4 × 4 × 3.14 = 50.24 square centimeter
The utilization rate of this paperboard is 50.24 (10x8) = 62.8%
Find the meaning of some symbols in mathematical formula
n
UD(n)t=∑max{0,sign(Ct-i+1—Ct-i)}
i=1
max{ sign(
N and I = 1 are up and down
Max {} is the maximum in brackets
Sign (x) or sign (x) is called sign function. In mathematics and computer operation, its function is to take the sign (positive or negative) of a certain number:
When x ≥ 0, sign (x) = 1;
When x
It is known that the sum of 5 / 2x ^ 5m + 2n + 2Y ^ 3 and - 4 / 3x ^ 6y ^ 3m-2n-1 is a monomial, and the binary oneness of M and N is listed
If sum is a monomial, then the degree of X and y are equal respectively
therefore
5m+2n+2=6
3m-2n-1=3
Add
8m+1=9
m=1
n=(4-5m)/2=-1/2
As shown in the figure, the cone AB is the diameter of the bottom surface, and the cone generatrix SA = AB = 2R, C is the cosine value of the angle formed by the straight line SC and AB on the different surface satisfying the sin angle ABC = 1 / 3
Make CD ‖ AB through C and intersect semicircle ACB at D, then ∠ SCD is the angle formed by a straight line of different planes
So ⊥ surface ABC is made through s, and the perpendicular foot is O, then o is the center of the bottom surface
SC=SA=2r,OC=AB/2=r,∴cosSCO=OC/SC=1/2
cosOCD=cosAOC=cos2∠ABC=1-2sin²ABC=8/9
∴cosSCD=cosSCO*cosOCD=4/9
I hope it can help you
How to divide 78 by 2
78 △ 2 = 39 checking calculation: 39 × 2 = 78
RELATED INFORMATIONS
- 1. How many four digit numbers can be made up of the four numbers 2345 without repetition? What is the sum of all these four digit numbers Come on - thank you
- 2. How to change a number into a number in billions
- 3. Use the four numbers 1, 3, 7 and 8, and use +, -, *, /, () to form the formula of the number 24
- 4. Use the four numbers of 1, 4, 7 and 8, and use +, -, *, / or brackets to form the formula of 24
- 5. Let all possible values of continuous random variable X be in the interval [a, b], and its density function be f (x)
- 6. If a and B are known to be real constants, then f (x) = a | X-B | + 2 is an increasing function in the interval [0, positive infinity], if and only if
- 7. The function f (x) = Tan (x + φ) is odd if and only if φ = k π K ∈ Z why is the false proposition TVT
- 8. Let y = f (x) be an odd function on R, and if x ∈ R is, there is f (x + 2) = - f (x). If - 1 ≤ x ≤ 1, f (x) = SiNx, let x ∈ [1,5], The analytic expression of F (x)
- 9. Let f (x) = 1-x under the root sign, then G (x) = the domain of definition of F (2 / x) + F (2 / x)
- 10. Which of the functions y = f (x-a), y = f (x + a) and f (a + x) = f (A-X) is a necessary and sufficient condition for the image to be symmetric with respect to the straight line x = a, or are they both correct
- 11. According to the law of the first three numbers, write the last number: 2345 & nbsp; 3452 & nbsp; 4523______ ．
- 12. Who can teach me how to calculate this mathematical formula? The problem is as follows: (I can't draw a picture, only by saying) there is a straight line from point a to point B. We know that its length is a, and there is a point C between two points AB, AC = BC, AC + BC = AB or A. at this time, draw a line perpendicular to ab from point C to point D, and we know that the length of CD is B, which is not equal to a, How long is the length of this arc? (for example: a = 20 meters, B = 2 meters) how to calculate, and what is its formula? I hope which expert can give an accurate formula! I'm sorry, R & sup2; = (A / 2) & sup2; + (R-B) & sup2; why r = (A & sup2; + 4B & sup2;) / 8b, how to check its formula? In addition, can you explain how to work out the formula of ∠ AOD degree again? Trouble my friend!
- 13. 1. Given that {a} is an arithmetic sequence, and A3 = 10, a7 = 42, find A1, D, an, Sn 2. Given that {a} is an equal ratio sequence, and A1 = 1, A3 = 4, find A10, Sn
- 14. Since January 2014, I have made a fixed deposit of RMB 6000 every year. The end date of each deposit is January 2043. What is the total number of withdrawals at that time? The main thing is that I don't understand the interest rate, and I don't know what the interest rate is,
- 15. Assuming that all variables are integers, the value of the expression (a = 2, B = 5, a + +, B + +, a + b) is（ A、7 B、8 C、9 D、10
- 16. 3. Assuming that all variables are integers, the values of the expression (a = 2, B = 5, B + +, a + b) are () (1 point) a, 7 B, 8 C, 6 D, 2
- 17. Assuming that a and B are shaping variables, it is necessary to rewrite the mathematical expression 1 / AB into C language expression
- 18. If x is an integer variable, the mathematical relation cannot be expressed correctly: 5
- 19. If the variable has been correctly defined and assigned, the expressions in accordance with C language syntax are a = a + 7; B a = 7 + B + C, a + + C int (12.3% 4) d a = a + 7 = C + B
- 20. 11. Let a = b = D = true, C = e = false, the following logic operation expression value is true, there is () B.(((A∧B)∨C)∧D∧E) Why is B true ∧ true ∧ false? The result should be false?