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Solving the equation 4x-2 = 3-x
4x-2＝3-x
4x+x=3+2
5x=5
x=1
How to calculate (99 * 99 + 99) / 0.99 with simple calculation method
(99*99+99)÷0.99
＝99*(99+1)÷0.99
=(99÷0.99)x100
=100x100
=10000
Put two beakers containing dilute hydrochloric acid of equal mass and solute mass fraction on the left and right sides of the tray balance, adjust to balance, and add iron and magnesium of equal mass into the two beakers respectively. After the reaction stops, please judge
1. If the balance is still in balance, there must be no residue in the beaker______
2. If the balance is out of balance, the pointer must be tilted______ On one side of the road
It's a bit of trouble, but please explain why for me
1. Hydrochloric acid 2. Iron releasing
Because when the same mass of Fe and Mg reacts with enough hydrochloric acid, the mass of hydrogen generated by the reaction of Mg and hydrochloric acid is larger. If the hydrochloric acid is sufficient (or for one of them is sufficient), the balance can not be balanced; while the amount of gas generated when a certain mass of hydrochloric acid reacts with enough iron and magnesium is equal. Now the balance is balanced, That means that the weight reduction on both sides is equal, so the mass of hydrogen generated on both sides is equal, which means that hydrochloric acid is insufficient and iron and magnesium are surplus
The balance is out of balance because there is more gas and less weight in the beaker with magnesium than that with iron, so the balance inclines to the side with iron
Fe + 2HCl = = FeCl2 + H2 difference
Relative atomic mass 56 2 54
56g 2g 54g
Mg+2HCl==MgCl2+H2
Relative atomic mass 24 2 22
24g 2g 22g
The original price of a commodity is ()
A. 0.9aB. 1.1aC. a0.9D. a1.1
The original price of each product is a △ 0.9 = a0.9 yuan
The definition field of function y = - 2 / X is, and the value field is
Definition field: X ≠ 0 value field: (- ∞, 0) ∪ (0, + ∞)
When a commodity with a purchase price of 40 yuan is sold at 50 yuan, 500 pieces can be sold every month. It is known that every 2 yuan increase in the price of the commodity will reduce its monthly sales by 20 pieces. In order to ensure a profit of 8000 yuan per month, what is the unit price?
Suppose the unit price should be set as X Yuan, then according to the meaning of the title: & nbsp; (x − 40) [500 − 202 (x − 50)] = 8000, the solution equation is: X1 = 60, X2 = 80. Therefore, in order to ensure the monthly profit of 8000 yuan, the unit price should be set as 60 yuan or 80 yuan
If a commodity is sold at a reduced price according to the season, if it is reduced by 10% at the current price, it will still make a profit of 180 yuan. If it is reduced by 20%, it will lose 240 yuan. How much is the purchase price of this commodity?
Suppose the current price is x yuan, from the meaning of the question: (1-10%) x-180 = (1-20%) x + 240, & nbsp; & nbsp; & nbsp; & nbsp; 90% x-180 = 80% x + 240, & nbsp; 90% x-180-80% x = 80% x + 240-80% x, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 10% x-180 = 240, & nbsp; 10% X
What is the significant number of 3.20 times 10 to the fifth power
3 significant numbers
A proof of mathematical algebra
It is proved that for any natural number n, the 2005 power of (n + 1) + the 2005 power of (n-1) + the 2005 power of (n-1) - 3N can always be divisible by 10
There is a skill in this problem. 2005 = 4 * 501 + 1. You can analyze that the single digits of 1, 5, 6 and 10 are unchanged no matter how many times they are power. The digit of 4 is a cycle of 4 and 6, and 9 is a cycle of 9 and 1. 2 is a cycle of 2, 4, 8, 6; 3 is a cycle of 3, 9, 7, 1; 7 is a cycle of 7, 9, 3, 1; 8 is a cycle of 8, 4, 2, 6
What are concrete labor and abstract labor? Please give examples to explain them
RT, please don't copy some political economy sayings
Hope to understand the predecessors can easily understand the explanation, it is best to add examples
For example, the production of a part is embodied in the specific labor of the producer's brain design and hands-on production, and in the abstract labor, no matter how special you design a special mode of production, it reflects the commonness of your mental and physical consumption, which is embodied in all social labor, that is, abstract labor
Abstract labor and concrete labor are not two kinds of labor, but two aspects of labor. They can not be separated from each other. Concrete labor is from the perspective of producers, while abstract labor is from the perspective of society. This is why concrete labor can only be recognized by society through commodity exchange and be reduced to abstract labor (to obtain value)
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