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If AB = 0, then a = 0 is a false proposition
When a = 2, B = 0, ab = 0, but a = 2 ≠ 0
Since there is no air in space, it is a vacuum. How does the spaceship accelerate?
If there is no air, there will be no backstepping. What is the acceleration?
The mass m of the spacecraft flying at the speed V burns the fuel to produce high temperature and high pressure gas. The gas with mass m ejects from the nozzle of the spacecraft tail at high speed v. due to the conservation of momentum, there are some problems
MV=(M-m)V'-mv
V'=(MV+mv)/(M-m)
So V '> V, that is, the spacecraft is accelerated
4-2 ╳ = 1, what is the unknown number x equal to?
2x=3
x=3/2
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A car is driven to the destination 180 km away from the starting place. It will drive at the original planned speed within the first hour after departure, and at the original speed after one hour
Drive at 1.5 times of the original speed, arrive at the destination 40 minutes earlier than the original plan, and calculate the speed of the previous hour
Let the speed of the previous hour be x km / h
From the meaning of the title, 180-x / X - 180-x / 1.5x = 2 / 3
Multiply both sides of the equation by 3x
540-3x-(360-2x)=2x
Merge similar items
180 = 3x
The solution is x = 60
It is proved that x = 60 is the solution of the original equation
A: the speed of the previous hour was 60 km / h
If x = 5 is the solution of the equation 2x-7 / 4 + x-m / 3 = 3x + 2 / 12, find the value of M
Let x = 5 be taken into the original formula
3/4+(5-m)/3=17/12
(5-m)/3=8/12=2/3
5-m=2
m=3
A car goes back and forth between a and B. it travels 80 km for the first time, 60 km per hour for the return, and 70 km for the second time
The round trip time ratio is ()
Let the distance be x (x / 80 + X / 70) / (x / 60 + X / 70) = (70 + 80) / (70 * 80) / (60 + 70) / (60 * 70) = (150 / 5600) * (4200 / 130) = (15 * 42) / (56 * 13) = (15 * 6) / (8 * 13) = (15 * 3) / (4 * 13) = 45 / 52, so the answer is 45 / 52
Given a (- 2,1), B [- 1,2), then AUB =?
Analysis:
This kind of painting number axis to solve!
First, draw the range of a (- 2,1) on the number axis
Then draw the range of B [- 1, 2) on the number axis,
Take all the ranges represented by both as (- 2,2)
That is a ∪ B = (- 2,2)
If you don't understand, you can continue to ask,
Factorization: 1. (x2 + 2x) 2-x2-2x-2 2. Simplification: 1 + X + X (1 + x) + X (1 + x) 2 +... + X (1 + x) 1998
3. When X-Y = 1, find the algebraic formula: x4-xy3-x3y-3x2y + 3xy2 + Y4
Complement (power after letter)
① (X & sup2; + 2x) & sup2; - X & sup2; - 2x-2 = (X & sup2; + 2x) & sup2; - (X & sup2; + 2x) - 2 cross multiplication = (X & sup2; + 2x-2) (X & sup2; + 2x + 1) = (X & sup2; + 2x-2) (x + 1) & sup2; ② (1 + x) + X (1 + x) + X (1 + x) & sup2; +... + X (1 + x) ^ 1998 = (1 + x) [1 + X + X + X (1 + x) +... + X (1 +
Four fifths of the fruits are transported from the fruit shop, of which three fifths are apples, one fifths are pears, one fourth are bananas, and the rest are oranges
How many tons of apple, pear, banana and orange
Apple: 4 / 5 × 3 / 8 = 3 / 10 = 0.3 (ton)
Pear: 4 / 5 × 1 / 5 = 4 / 25 = 0.16 (ton)
Banana: 4 / 5 × 1 / 4 = 1 / 5 = 0.2 (ton)
Orange: 4 / 5 - (0.3 + 0.16 + 0.2) = 0.8-0.66 = 0.14 (ton)
There is a bottle of alcohol, the first time pour out 2-3 and 80g, then pour back 140g; the second time pour out 3-4 of the alcohol in the bottle, then there is 90g left in the bottle
How much alcohol is there
The short ideas should be written clearly
(90*4-140+80)/(1/3)=900
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