The ratio of boys to girls is four fifths, and boys account for four ninths of the total

The ratio of boys to girls is four fifths, and boys account for four ninths of the total

yes

The boys in a class account for four ninths of the total number of students in the class. After several girls are transferred, there are still 40 students left in the class. At this time, the girls account for two fifths of the total number of students in the class
It is necessary to calculate the process and not use the quadratic equation

Among the 40 students in the class, girls account for two fifths
There are 16 girls and 24 boys in 40 × 2 / 5
All of them are girls, so there were 24 boys before they left
Boys make up four out of nine of the class at the beginning
Divide 24 by four out of nine and there are 54 students in the class
The original number of girls 54-24 = 30
The number of transferred girls is 30-16 = 14

The number of boys is 9 less than 4 / 5 of the class, and the number of girls is 13 less than 3 / 4 of the class

Problem solving:
Set Boys: X class: y girls: y-x
4/5y-9=x
3/4y-13=y-x
y=40 x=23

Please write the Taylor formula of order n (n > 3) of function f (x) = LNX at x = 2

f(2)=ln2
f'(2)=1/2
f''(2)=-1/4
f'''(2)=1/4
open
f(x|x=2)=ln2+1/2*(x-2)-1/4 /(2!) *(x-2)^2+ 1/4 /(3!) *(x-2)^3+o(x)

Boys in a class account for 60% of the class. How many% more boys than girls?
Which is right?
1、60%-（1-60%）=20%
2、（60%-40%）/40%=50%
Another way: there are 100 students in a class. Boys account for 60% of the class. How many% more boys than girls?

More than 20 percent
Your answer 1 is correct. This is a common saying. When XX is more than XX, it is usually the ratio of the two. The more is the more

What is minus five times one plus one in five
process

-5*1+1/5=-24/5
24 out of 5

5. If the value of each term of a sequence is greater than zero, the limit of the sequence must be greater than zero
Right or wrong?

No, it could be 0

Xiaodong's mother received 270 bonus from her unit, including 80 pieces of 2 yuan, 5 yuan and 10 yuan, and the number of 5 yuan and 10 yuan is equal. How about these three kinds of currency

Let X of 5 and y of 2
2x+y=80
2y+15x=270
x=10,y=60
Then 60 sheets of 2, 10 sheets of 5 and 10 sheets of 10

9 10 19 29 48 () () find the law

9 plus 10 equals 19, 10 plus 19 equals 29, 19 plus 29 equals 48, so the rule of these numbers starts from 19, and the sum of the first two numbers equals the third number!

How to prove that the sum of squares of n natural numbers equals n (n + 1) (2n + 1) / 6,3q

(n + 1) ^ 3 = n ^ 3 + 3N ^ 2 + 3N + 1, we can get (n + 1) ^ 3-N ^ 3 = 3N ^ 2 + 3N + 1, then there is n ^ 3 - (n-1) ^ 3 = 3 (n-1) ^ 2 + 3 (n-1) + 1.. 3 ^ 3-2 ^ 3 = 3 * (2 ^ 2) + 3 * 2 + 1 ^ 2-1 ^ 3 = 3 * (1 ^ 2) + 3 * 1 + 1. Add the two ends of these n equations to get: (n + 1) ^ 3-1 = 3 (1 ^ 2 + 2 + 3 ^ 2 +. + n ^ 2) + 3 (1 + 2 + 3 +