1/11-11/31+2/11-12/31+3/11-13/31…… +10 / 11-20 / 31 = simple method Fast in three minutes

1/11-11/31+2/11-12/31+3/11-13/31…… +10 / 11-20 / 31 = simple method Fast in three minutes

This question is very simple. You add all the denominators of 11, add all the denominators of 31, and subtract them. The answer is 5-5 = 0

157*23/156
Is a score calculation problem, the best answer is simple algorithm

156*23/156+23/156=23+0.1474=23.1474

2003+20032003+… +20032003… 2003 (2003) / 2004 + 2004, 2004 + +20042004… What is 2004 equal to
In the middle / is the fractional line, the request is the simple computation

Original formula = 2003 (1 + 10001 + 10001 +...) /2004（1+10001+100010001+……） =2003/2004

It is known that a = a + 2, B = a2-a + 5, C = A2 + 5a-19, where a > 2. (1) prove that B-A > 0, and point out the size relationship between a and B; (2) point out which is bigger between a and C? Give reasons

(1) B-A = (A-1) 2 + 2 > 0, so b > A; (2) C-A = A2 + 5a-19-a-2, = A2 + 4a-21, = (a + 7) (A-3). Because a > 2, so a + 7 > 0, so when 2 < a < 3, a > C; when a = 3, a = C; when a > 3, a < C

A simple operation of 1 / 4 divided by 1 / 5 minus 3 / 4
A simple operation of 5 out of 7 division {(1 minus 3 out of 4) division by 3 out of 20}

1 / 4 △ 1 / 5-3 / 4
=5/4-3/4
=1/2
5 / 7 ^ {(1 minus 3 / 4) ^ 3 / 20}
=5/7÷{1/4÷3/20}
=5/7÷5/3
=3/7

If one root of the equation x & # 178; - 2 (1-A) x + 3A + 1 = 0 is greater than 1 and the other root is less than 1, the value range of a is obtained

First, the discriminant is greater than 0
4(a-1)²-4(3a+1)>0
a²-2a+1-3a-1>0
a²-5a>0
a> 5 or a

1. On Sunday, Xiao Ming went to the Cultural Palace to rehearse his dance. He traveled 1 / 2 kilometer in 1 / 5 hour. At this speed, how long does it take him to get to the Cultural Palace
2. A piece of land has 9 / 10 hectare, which can be ploughed by 4 tractors in 2 / 3 hours. How many hectare does each tractor plough on average?

1) (1 / 2) km divided by (1 / 5) H = (5 / 2) km / h
(5 / 2) km / h times 4 km = 10 hours
A: at this speed, it takes him 10 hours to get to the Cultural Palace
(do you understand? If you don't understand, ask again)
2) (9 / 10) divided by 4 and then divided by (3 / 2)

A cuboid water tank is 1.2m long, 0.8m wide, 0.4m high and 30cm high. After putting a rectangular iron block with a length of 0.6m and a width of 0.5m, the water is just full
The height of the cylinder,

Didn't you tell me everything? What else do you want
If you want to find the height of a rectangular iron block, calculate it as follows
1.2*0.8*(0.4-0.3)/(0.6*0.5)=0.32

What's the equivalent of seven out of 24

24 out of 7

Given the equal ratio sequence, an > 0, S3 = 6, a7 + A8 + A9 = 24, what is the common ratio in the equal ratio sequence and how to calculate it?

S3 = 6 leads to A1 = 3 / (1 + Q + Q & # 178;) A7 + A8 + A9 = 24 leads to a1q ^ 6 (1 + Q + Q & # 178;) = 24 3Q ^ 6 = 24 q = radical 2