What is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 +... + 2012

What is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 +... + 2012

=（1+2012）*2012/2=2025078

1/2+5/6+11/12+19/20+29/30+…… +N-square-n-1 / N (n-1)

A total of n-1 terms, the original formula = (1-1 / 2) + (1-1 / 6) + (1-1 / 12) + (1-1 / 20) + (1-1 / 30) +. + (1-1 / N (n-1)) = n-1 - (1 / 2 + 1 / 6 + 1 / 12 + 1 / 20 + 1 / 30 + +1/n(n-1))= n-1 -(1-1/2 + 1/2-1/3 + 1/3-1/4 + 1/4-1/5 + 1/5-1/6 +.+ 1/(n-1)-1/n )= n-1 -(1...

Solving inequality: LX + 1L > 2-x

x2
Not established
Give up
x>-1
x+1>0
So x + 1 > 2-x
x>1/2
Satisfy x > - 1
therefore
x>1/2

After a shopping mall bought two kinds of goods, the price of goods a and B increased by 50% and 40% respectively as the price. On New Year's day, the shopping mall was engaged in promotional activities, and the price of goods a was eight
A customer pays 538 yuan to buy a piece of commodity a and B, and the total profit of the store is 88 yuan. What is the total purchase price of the two commodities?

Let a's price be x and B's price be y
The selling price of a is 1.5x and that of B is 1.4y
Then 1.5x * 0.8 + 1.4y * 0.85 = 538
538-x-y=88
The solution is x = 250, y = 200
Then the total purchase price is 200 + 250 = 450

What is undergraduate? What are 1a, 2a, 3a, 1b, 2b, 3b?

Undergraduate refers to full-time undergraduate, most of them have both undergraduate diploma and bachelor's degree certificate. 1a is one, first-class undergraduate, one batch of admission. 2a is two, second class undergraduate, two batches of admission. 3a is junior college. Without 1b, 2b is ordinary undergraduate, 3b is junior college

At 8:00 a.m., a truck drove from city a to city B at the speed of 48 km / h, and at 10:00 a.m., a bus drove to city B at the speed of 70 km / h~
In order to drive safely, the distance between workshops should not be less than 8 km. When should trucks stop at the latest to let buses pass?
In order to drive safely, the distance between workshops should not be less than 8 km. When should trucks stop at the latest to let buses pass?
Be specific!

That is, the truck should stop 8 km away from the bus at the latest
（48*2-8）/（70-48）
=88/22
=Four hours
Four hours after ten in the morning is two in the afternoon
Trucks should stop at 2 pm at the latest to let buses pass by

What's one plus seven fifths

Twelve fifths

A and B depart from a and B at the same time. For the first time, they meet 75 km away from A. after meeting, they continue to move forward and return to their destination. For the second time, they meet 55 km away from B. A and B are far away from each other______ Kilometers

75 × 3 = 225 (km), 225-55 = 170 (km)

Equation 3x-1 / 6 = 3-2x-3 / 2

The left and right sides of the equation are multiplied by 6
18X-1=18-12X-9
30X=10
X=1/3

If points a (a, 0), B (0, b), C (1, - 1) (a > 0, B < 0) are collinear, then the minimum value of A-B is equal to ()
A. 4B. 2C. 1D. 0

Analysis: ∵ a, B, C are collinear, ∵ KAB = KAC, that is, B − 00 − a = − 1 − 01 − a, ∵ 1a-1b = 1. From a > 0, B < 0, we can get - BA > 0, - AB > 0, ∵ A-B = (a-b) (1a-1b) = 2-ba-ab = 2 + [(- BA) + (- AB)] ≥ 2 + 2 = 4 (when a = - B = 2, take the equal sign), so we choose a