｜1/2001-1/2000｜+｜1/2000-1/1999｜-｜1/1999-1/2001｜=? 1/2+1/4+1/8+...+1/256+1/512+1/1024=? 1+2+3+...+1997+1998+1999=?

｜1/2001-1/2000｜+｜1/2000-1/1999｜-｜1/1999-1/2001｜=? 1/2+1/4+1/8+...+1/256+1/512+1/1024=? 1+2+3+...+1997+1998+1999=?

=1/2000-1/2001+1/1999-1/2000+1/2001-1/1999=0=1/2+1/4+1/8+...+1/256+1/512+1/1024+1/1024-1/1024=1/2+1/4+1/8+...+1/256+1/512+1/512-1/1024=...=1-1/1024=1023/1024=(1+1999)*1999/2=2000/2*1999=1000*1999=1999...

1.2A square + b square - 2Ab + 4A + 4 = 0 for ab
2. If x square + 3x + 1 = 0, find the - 2 power of x square + X, the fourth power of X + one fourth power of X
The 50 times of 3.2 can be divided by two numbers between 60 and 70
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2A & sup2; = A & sup2; + A & sup2;, then the original formula can be rewritten as (a-b) & sup2; + (a + 2) & sup2; = 0, then a = B, a = - 2, ∵ B = - 2, ab = 42. ∵ x ≠ 0 ∵ the equation is divided by X to get x + 3 + 1 / x = 0, X & sup2; + 1 / X & sup2; = (x + 1 / x) & sup2; - 2 = (- 3) & sup2; - 2 = 7 X4 + 1 / X4 = (x & S

Since August 1, 2004, the new electricity price policy has been implemented for urban and rural residents in Zhejiang Province. XiaoCong's family has installed a new electricity meter this year. He learned that residents who have installed "one meter for each household" will increase the electricity price step by step according to the electricity consumption (the electricity consumption indicated by each user's electricity meter), and the part of electricity price below 50 kWh (including 50 KWH) will not be adjusted; The price of 51-200 kwh will be increased by 0.03 yuan per kilowatt hour, and the price of over 200 kwh will be increased by 0.10 yuan per kilowatt hour. It is known that the price before the adjustment is 0.53 yuan per kilowatt hour
(1) If XiaoCong's electricity consumption in October is 130 kwh, how much will XiaoCong pay in October?
(2) It is known that XiaoCong's electricity consumption in October is kwh. Please fill in the blanks below:
① In case of kwh, the electricity charge payable by XiaoCong's family in October is___________ Yuan;
② In case of kwh, the electricity charge payable by XiaoCong's family in October is___________ Yuan;
③ In case of kwh, the electricity charge payable by XiaoCong's family in October is___________ Yuan
(3) If the electricity charge payable by XiaoCong's family in October is 96.50 yuan, what is the electricity consumption of XiaoCong's family in October?

(1) 0.53 * 50 + (130-50) * (0.53 + 0.03) = 60.1 yuan
(2) 20 yuan for 40 watts, 54.50 yuan for 100 watts and 142.00 yuan for 250 watts
(3) Because the cost of 50 kwh is 26.50 yuan and that of 200 kwh is 110.50 yuan, the electricity cost of 96.50 yuan is less than 200 watts and more than 50 watts. If the power consumption is (50 + x) watts, then 50 * 0.53 + 0.56x = 96.50 and x = 125 watts

Zhang Chen processed 40% of the total. Wang Jun and Liu Liang processed 2:3 parts. Liu Liang processed 360 parts
How many parts are there in this batch?

Wang Jun: 360 × 2 △ 3 = 240
(240 + 360) / (1-40%) = 1000

1、 A ring road is 18 kilometers in circumference. Party A and Party B start from the same place on the road at the same time, turn their backs and meet two hours later. It is known that Party A is 3 kilometers slower than Party B every hour
(1) What's the speed of a and B (just write an answer)
(2) If two people start from the same place on the road at the same time and go in the same direction, when will they meet again
2、 A middle school student arranges the playground by himself. The first grade students finish it in 7.5 hours, and the second grade students finish it in 5 hours. If the first grade and second grade students work together for 1 hour, then the second grade students finish the rest separately, how many hours? (write the steps)

Let a's speed be x, then B's speed be x + 3 (1) 2x + 2 (x + 3) = 18, x = 3x + 3 = 6. A: A's speed is 3 km / h, and the speed is 6 km / h

There are two granaries, a and B. A stores 100 tons of grain, and B stores 80 tons of grain. In order to make the stock ratio of a and B 2:7, how many tons does a need to transport to B

Warehouse a needs to transport 60 tons to warehouse B
2+7=9,100+80=180
180 * (2 / 9) = 40 (tons)
180 * (7 / 9) = 140 (tons)
So warehouse a needs to transport 60 tons to warehouse B

X-0.7x = 8x0.6 (solution equation)

x-0.7x=8*0.6
0.3x=4.8
x=16

Mathematics problem 33 + 29 * 33 = how to calculate with a simple method

33+29*33
=33x（1+29）
=33x30
=990

It is known that the sum of the first n terms of {an} is Sn, A1 = 3, S3 = 39
(1) How to find the general term formula of the sequence {an}?
(2) If n numbers are inserted between an and an-1, so that these n + 2 numbers form an arithmetic sequence with tolerance DN, the proof is: 1 / D1 + 1 / D2 +. + 1 / DN

(1) S3 = a1 + A2 + a3 = A1 (1 + Q + Q ^ 2) = 391 + Q + Q ^ 2 = 13q ^ 2 + q-12 = 0q1 = 3, Q2 = - 4 (contradictory to each positive number, rounding off) an = A1 Q ^ (n-1) = 3 * 3 ^ (n-1) = 3 ^ n (2) an - a'n-1 '= 3 ^ n - 3 ^ (n-1) = 2 * 3 ^ (n-1) according to the meaning of the question an - a'n-1' = (n + 1) DN, so DN = [2

How to calculate 34 out of 35 times 36?

34 out of 35 times 36
=34 out of 35 times (35 + 1)
=34 × 35 of 35 + 34 × 1 of 35
=34 + 34 / 35
=34 / 35