High school mathematics probability problem calculation formula solution Two C (n, m) together how to calculate, for example, this formula: C (4,2) C (4,2) - 2 equal to how much to find the specific process! Thank you

High school mathematics probability problem calculation formula solution Two C (n, m) together how to calculate, for example, this formula: C (4,2) C (4,2) - 2 equal to how much to find the specific process! Thank you

C（4 ,2）C（4 ,2）-2
=[（4×3）÷（2×1）]×[（4×3）÷（2×1）]﹣2
=6×6-2
=34
(4 * 3 * 2 / 2 * 2) square-2 equals 34
（4×3/ 2）×（4×3／2）－2＝34
C(4,2)=A(4,2)/2!=4!/2!/2!=6 C(4,2)C(4,2)-2=6*6-2=34
c(4,2) = (4x3)/(2X1)=
c(n,m)=[nx(n-1)x(n-2)......x (m+1)]/[mx(m-1)x(m-2)....x 1]
C（n,m）= n(n-1)(n-2)...(n-m+1) / m!
For example, C (10,6) = (10x9x8x7x6x5) / (6x5x4x3x2x1).
I hope I can help you
How to calculate the probability a of high school mathematics? Please tell me what the formula is? Thank you!
A (n, m) is a combination formula, which means that there are several methods to select m numbers from n numbers for random arrangement. The number is the same, but the order is different, and the method is different
A (n, m) is the multiplication of the first m numbers from n to 1. A (n, m) = n * (n-1) * (n-2) *... * (n-m + 1)
Let me give you an example, a (4 below, 3 above) = 4 * 3 * 2
Another example is a (n, 3) = n * (n-1) * (n-2)
The narration is not good. If you don't understand, you can continue to ask questions
A (n, m) where n is lower and M is upper, obviously m ≤ n is required
A(n,m)=n(n-1)*(n-2)*…… (n-m+1)
N is divided by M
On probability and permutation combination
1. There are four students in a class participating in volunteer activities. The four students are assigned to three different projects a.b.c. each of them is assigned at least one person. If a does not ask for project a, the different allocation schemes are ()
2. There are five different books, including two Chinese books. If they are randomly placed side by side on the same shelf, the probability that the books of the same subject are not adjacent ()
3. There are two red balls and two white balls in the two bags of a and B. first transfer from bag a to bag B, and then transfer any ball from bag B to bag a. the probability of one red ball in bag a is ()
one point two four
2.2 /5
3.4/9
1. There are three cases: (1) only Chinese is adjacent, can be regarded as a book, mathematics can only be inserted, that is, 2 * 2 * 3 * 2 = 24, in which the first 2 is the arrangement of two Chinese books, the second 2 is Chinese
Slope formula between two points
K = (y2-y1) / (x2-x1) where (x1, Y1), (X2, Y2) are the coordinates of two known points
Simplify the following formulas by using the base changing formula of logarithm
1. Loga C (upper case) × logC a (upper case) 2. Log2 3 [upper case) × log3 4 [upper case] × log4 5 (big) × log5 2 (big) 3. {log4 3 (big) log8 3 (big)} × {log3 2 (big) log9 2 (big)}
1.1 2.1
What is the slope formula
Finding the slope of a given point~
K = (y2-y1) / (x2-x1) where (x1, Y1), (X2, Y2) are the coordinates of two known points
It seems that it should be high / bottom edge long. After the college entrance examination, it will be returned to the teacher immediately~~~~~~~~~~~~~~~~
K = (y2-y1) / (x2-x1) where (x1, Y1), (X2, Y2) are the coordinates of two known points
k=tanx
k=(y2-y1)/(x2-x1)
K = (y2-y1) / (x2-x1), that's right
Simplify the following formula by using the base changing formula of logarithm
(log4 3+log8 3)(log3 2+log9 2)
How can I find two. Which one is right
Log4 3 + log8 3 = Lg3 / LG4 + Lg3 / LG8 = Lg3 / 2lg2 + Lg3 / 3lg2 = (1 / 2 + 1 / 3) * (Lg3 / LG2) = (5 / 6) * (Lg3 / LG2) log3 2 + log9 2 = LG2 / Lg3 + LG2 / lg9 = LG2 / Lg3 + LG2 / 2lg3 = (1 + 1 / 2) * (LG2 / Lg3) = (3 / 2) * (LG2 / Lg3), so the original formula = (5 / 6) * (3 / 2) = 5 / 4
Primary school conversion formula
0.4 km = () M
1200 m = () km
284g = () kg
532 cm = () M
1480m = () km
1.5km = () M
1670 M = () decimeter
1.48km = () M
0.4 km = (400) M
1200 m = (1.2) km
284 g = (0.284) kg
532 cm = (5.32) M
1480m = (1.48km)
1.5km = (1500m)
1670 M = (16700) decimeter
1.48 km = (1480) M
Four hundred
One point two
zero point two eight four
five point three two
one point four eight
one thousand and five hundred
sixteen thousand and seven hundred
one thousand four hundred and eighty
Four hundred
One point two
zero point two eight four
five point three two
one point four eight
one thousand and five hundred
sixteen thousand and seven hundred
one thousand four hundred and eighty
Four hundred
One point two
zero point two eight four
five point three two
one point four eight
one thousand and five hundred
sixteen thousand and seven hundred
one point four eight
To simplify with logarithm formula
Logac times logca
Log bottom left 2 right 3 times log bottom left 3 right 4 times log bottom left 4 right 5 times log bottom left 5 right 2
1、
The original formula = (LGC / LGA) (LGA / LGC) = 1
2、
Original formula = (Lg3 / LG2) (LG4 / Lg3) (lg5 / LG4) (LG2 / lg5)
Approximate points
=1
What are the conversion formulas of primary school and the improvement rate?
Length part: millimeter, centimeter, decimeter, meter, the advance rate between them is 10
1000 m = 1 km 1 m = 10 decimeter 1 decimeter = 10 cm 1 cm = 10 mm 1 m = 100 cm
Area unit: square meter, square decimeter, square centimeter, square millimeter, the rate of progress between them is 100
1 square meter = 100 square decimeter 1 square decimeter = 100 square centimeter 1 square centimeter = 100 square millimeter
Land area: mu (less used), hectare, square kilometer, the rate between them is 100
1 hectare = 100 hectare = 100 hectare = 1 hectare = 100 hectare
1 hectare = 10000 square meters 1 square kilometer = 1000000 square meters
Unit of weight: gram, kilogram, ton. The rate of advance between them is 1000
1 ton = 1000 kg 1 kg = 1000 g
Time unit: hour, minute and second. The progression rate between them is 60
1 hour = 60 minutes 1 minute = 60 seconds
1 day = 24 hours, 1 year = 4 seasons (spring, summer, autumn and winter)
Ordinary year: the number of years is not a multiple of 4
Leap year: the number of years is a multiple of 4. If it is a century year, it is a multiple of 400
February is a special month, 28 days in a normal year and 29 days in a leap year