![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
What does the number 58 at the bottom of the plastic cup mean
58 in the triangle at the bottom of the cup means that the bottle is made of PC material. PC material is an amorphous, tasteless, odorless, nontoxic, transparent thermoplastic polymer, especially with impact resistance and good toughness. It can withstand liquid temperature from - 20 to + 120 degrees, and is suitable for filling boiling water
It's better to pour boiling water in glass
Numbers about the bottom of a plastic cup
I bought a cup in Tupperware. There is a triangle at the bottom of the cup, and there is a 71 inside. I heard that people can't put hot water. That kind of plastic is not good for human body. I also heard that the number 5 is better, and pp9 is also good. What do you mean by my seven? Can you hold hot water? Thank you
"7" means that this plastic product is made of PC material (polycarbonate). This kind of water cup is easy to release toxic substance bisphenol A, which is harmful to human body. In addition, do not heat this kind of cup and do not bask in the sun!
What's the meaning of a number in the triangle on the plastic bottle?
1: Pet polyethylene terephthalate
Common mineral water bottles, carbonated beverage bottles, etc. are easy to deform when heat resistance reaches 70 ℃, and harmful substances melt out. No. 1 plastic may release carcinogen DEHP after 10 months of use. Do not put it in the car in the sun; do not contain alcohol, oil and other substances
2: HDPE high density polyethylene
Common white medicine bottles, cleaning supplies, bath products. Do not use them as water cups or storage containers to hold other items. Do not recycle if the cleaning is not complete
3: PVC, PVC
Common raincoat, building materials, plastic film, plastic box, etc. good plasticity, low price, so it is very common to use, can only heat 81 ℃. When the temperature is high, it is easy to have bad substances, rarely used in food packaging. It is difficult to clean, easy to residue, do not recycle. If you pack drinks, do not buy
4: PE polyethylene
Common preservative film, plastic film, etc. when the temperature is high, there are harmful substances, toxic substances with food into the human body, may cause breast cancer, neonatal congenital defects and other diseases. Do not put preservative film into the microwave oven
5: PP polypropylene
The only way to make a drink is to put it in a microwave oven with a melting point of 167 ℃
6: PS polystyrene
Do not put it in the microwave oven to avoid releasing chemicals due to too high temperature. After filling acid (such as orange juice) and alkaline substances, it will decompose carcinogens. Avoid packing hot food with fast food boxes. Do not use the microwave oven to cook instant noodles
7: PC others
Common water bottle, space cup, milk bottle. Department stores often use this kind of water cup as a gift. It is easy to release the toxic substance bisphenol A, which is harmful to human body. Do not heat it when using, and do not directly sun it in the sun
There is a number 07 in the triangle of the plastic bottle. What's the meaning of the other below
This is the plastic recycling sign. There are 1-7 numbers in the triangle, and each number represents a kind of plastic container. The plastic recycling sign is formulated by the relevant agencies of the plastic industry in the United States. Different materials have different conditions of use. The small recycling sign at the bottom of the plastic product is like a small ID card of each plastic container. They are made of different materials and used differently
Special attention: don't buy 07 at ordinary times. Although it is the most, you will know after reading:
“01”——PET
(polyethylene terephthalate) mineral water bottles and carbonated beverage bottles are all made of this material. Beverage bottles can not be recycled to hold hot water. This material is heat-resistant to 70 ℃ and is only suitable for warm or frozen drinks. When it is filled with high-temperature liquid or heated, it is easy to deform and some substances harmful to human body are dissolved. Moreover, scientists found that this plastic product may release carcinogens after 10 months of use, It is toxic to human body. Therefore, the drink bottle should be discarded when it is used up. It should not be used as a water cup or as a storage container to hold other items, so as not to cause health problems
“02”——HDPE
High density polyethylene (HDPE) plastic containers for cleaning products and bath products, as well as the plastic bags currently used in supermarkets and shopping malls, are mostly made of this material, which can withstand high temperature of 110 ℃. The plastic bags marked with food can be used to hold food. The plastic containers for cleaning products and bath products can be reused after careful cleaning, but these containers are usually not easy to clean, Residue of the original cleaning supplies, become a hotbed of bacteria, cleaning is not thorough, it is best not to recycle
“03”——PVC
(PVC) according to reports, the toxic and harmful substances easily produced by this kind of plastic products come from two aspects, one is the monomolecular vinyl chloride that has not been fully polymerized in the production process, and the other is the harmful substances in plasticizers. These two substances are easy to precipitate when they encounter high temperature and grease, and the toxic substances are easy to cause cancer when they enter the human body with food, Containers made of this material are rarely used for packing food. If used, do not let it be heated
“04”——LDPE
Low density polyethylene (LDPE) preservative film and plastic film are all made of this kind of material. The heat resistance is not strong. Generally, the qualified PE preservative film will melt when the temperature exceeds 110 ℃, leaving some plastic preparations that cannot be decomposed by human body. Moreover, when the food is wrapped with preservative film for heating, the oil in the food will easily dissolve the harmful substances in the preservative film, First, take off the wrap
"05" - PP
(polypropylene) microwave oven lunch boxes are made of this material. They are resistant to high temperature of 130 ℃ and have poor transparency. This is the only plastic box that can be put into the microwave oven and can be reused after careful cleaning. It should be noted that some microwave oven lunch boxes are made of No. 05 PP, but the box cover is made of No. 06 PS (polystyrene)) with good transparency but not high temperature resistance, So it can't be put into the microwave oven together with the box. To be on the safe side, take off the cover before putting the container into the microwave oven
“06”——PS
(polystyrene) this material is used to make bowls of instant noodle boxes and foaming fast food boxes. It is heat-resistant and cold resistant, but it can not be put into the microwave oven to avoid releasing chemicals due to high temperature. It can not be used to contain strong acids (such as orange juice) and strong alkaline substances, because it will decompose polystyrene which is not good for human body. Therefore, you should try to avoid packing hot food with fast food boxes
“07”——PC
PC and other kinds of PC are widely used materials, especially in the manufacture of milk bottles and space cups, which are controversial because they contain bisphenol A. experts point out that in theory, as long as bisphenol A is 100% converted into plastic structure in the process of making PC, it means that there is no bisphenol A in the product, let alone release it, Therefore, special attention should be paid when using this plastic container
If your water bottle number is 07, the following methods can reduce the risk: do not heat it when using, do not use a dishwasher or a dish dryer to clean the water bottle. Before the first use, use baking soda powder and warm water to clean it, Dry naturally at room temperature. If the container is injured or damaged, it is recommended to stop using it, because if there are tiny pits on the surface of plastic products, it is easy to hide bacteria. Avoid repeated use of aging plastic utensils
A string of numbers, 1 / 2, 1 / 3, 2 / 3, 1 / 4, 2 / 4, 3 / 4, and so on, what is the 407th number
1 / 2, 1 / 3, 2 / 3, 1 / 4, 2 / 4, 3 / 4
Through observation, we can find that there is one denominator of 2, two denominators of 3 and three denominators of 4
∴n(n+1)÷2
When n = 28
28（28+1）÷2=406
The 407th number is 1 / 29
Excuse me: what are the ten thousand digits of the first 444 items in series 4, 444?
Should it be and?
4 44 444 4444
No need to consider after 44444 million
44444*(444-4)+4+44+444+4444
60000
In sequence 4, 444 What is the sum of the first 444 items in the ten thousand?
From 4 * 444 = 1776, (individual) 4 * 443 = 1772, (ten) 4 * 442 = 1768, (hundred) 4 * 441 = 1764, (thousand) 4 * 440 = 1760, (ten thousand) and 17600000176400017680017720 + 1776 -- -- 19560296, therefore, ten thousand is 6
If there is a group of numbers: - 1,1 / 2, - 1 / 3,1 / 4, and so on, what is the nth number
Please, hurry up!!!!!!!! Very urgent, very urgent!!!!! Want it now!!!!!! c'mon!!!
(- 1) nth power / N, n is a positive integer
Define a new operation: a * b = a + B-1, such as 3 * (- 2) = 3 + (- 2) - 1 = 0. Please calculate (- 1) * (- 3)=______ ．
(- 1) * (- 3) = (- 1) + (- 3) - 1 = (- 1) + (- 3) + (- 1) = - 5, so the answer is: - 5
For the rational number a, B, a new operation is defined, and its operation rule a, B = a-Ab △ B, try to find {3} (- 4)} 5 △ 7
3☆(-4)=[3-3*（-4）]÷（-4）= -15/4
-15/4☆5=[-15/4- (-15/4)*5 ]÷5=3
Original formula = 3 / 7
RELATED INFORMATIONS
- 1. The new operation * is defined as a * b = (1 / a multiplied by 1 / b) finding 3 * (4 * 5)
- 2. Grade seven Mathematics - 8-3 + 1-7, what do you read according to the meaning of "harmony"? What do you read according to the meaning of "operation"?
- 3. Speed by physical calculation Throw a ball horizontally at a speed of 15m / s at a height of 20m, and calculate (G is 10m / S2) regardless of air resistance (1) The speed of the ball at 10m above the ground (2) The speed at which the ball lands
- 4. If A-B = 5, then 3A + 7 + 5b-6 (a + 13b)=______ ．
- 5. Three digit ABC, the sum of all the two digits of a, B and C, multiplied by 1 / 3, is the three digit ABC =?
- 6. Two congruent triangle plates ade and ABC with 30 ° and 60 ° angles are placed as shown in the figure. E, a and C are in a straight line to connect BD. take the midpoint m of BD to connect me and MC. Try to judge the shape of △ EMC and explain the reason
- 7. As shown in figure 11.1-7, to know that a, D and E are on the same straight line, and △ bad ≡ ace Preferably before 15; 30
- 8. If two non-zero rational numbers a and B satisfy the relation a + B = 0, is their product a * B negative or positive
- 9. We say "two numbers subtract, the difference is less than the subtracted". After learning rational numbers, is this still true? For example
- 10. Define two kinds of operations △ and ＊, for any two numbers AB, there is a △ B = a + B-1, a ＊ B = B power-1 of a, and find the value of 2 ＊ [(3 △ 4) △ 2 ＊ 1]
- 11. High school inequality proof Given ABC = 1, and a, B, C are real numbers, it is proved that 1 / A + 1 / B + 1 / C + 3 / (a + B + C) > = 4
- 12. Some basic inequalities in Senior High School 1. For any x > 0, X / (the square of X + 3x + 1) ≤ a, then the value range of a is? 2. Let a > b > 0, then the minimum value of the square of a + 1 / AB + 1 / a (a-b) is?
- 13. High school a basic inequality problem! Given that x + 2Y = 1, both X and y are greater than 0, find the minimum value of 1 / x + 1 / y Because 1 / x + 1 / Y "2 √ (1 / XY) If and only if 1 / x = 1 / y is obtained, then x = y Substitute x + 2Y = 1 to get x = y = 1 / 3 So the minimum value is 2 / 3
- 14. As shown in the figure, in RT △ ABC, ∠ BAC = 90 °, ab = AC, and points m and N are on edge BC. (1) as shown in Figure 1, if am = an, prove: BM = CN; (2) as shown in Figure 2, if M and n are any two points on edge BC, and satisfy ∠ man = 45 °, then are line segments BM, Mn and NC possible to make equation Mn2 = BM2 + NC2 stand? If yes, please prove; if not, please give reasons
- 15. If a, B, C are the three sides of triangle ABC, and a (a-b) + B (B-C) + C (C-A) = 0, try to judge the shape of triangle ABC and explain the reason
- 16. In the triangle ABC, we know that a = 18. B = 22. Angle a = 45 degrees, then the number of such triangles is?
- 17. A true fraction multiplied by a number must be smaller than that number
- 18. If a number is multiplied by a true fraction, the product must be larger than that number______ (judge right or wrong)
- 19. If a and one-half B are opposite to each other, and B is not equal to 0, then the reciprocal of a is 2 c-2b D-B of A2B
- 20. A is a number that is not equal to 0. Please explain which of a + 3 / 5 and a multiplied by 3 / 5 has the larger result