Tốc độ bay hơi của chất lỏng không phụ thuộc vào yếu tố nào sau đây?

A. Thể tích của chất lỏng

B. Gió

C. Nhiệt độ

D. Diện tích mặt thoáng của chất lỏng

Làm ra đi rồi hãy nói. Trình bày rõ ràng giúp mình nha bạn.

M = 3xyz - 3x2 + 5xy - 1

N = 5x2 + xyz - 5xy + 3 - y

M + N = 3xyz - 3x2 + 5xy - 1 + 5x2 + xyz - 5xy + 3 - y

= -3x2 + 5x2 + 3xyz + xyz + 5xy - 5xy - y - 1 + 3

= 2x2 + 4xyz - y +2.

M - N = (3xyz - 3x2 + 5xy - 1) - (5x2 + xyz - 5xy + 3 - y)

= 3xyz - 3x2 + 5xy - 1 - 5x2 - xyz + 5xy - 3 + y

= -3x² - 5x² + 3xyz - xyz + 5xy + 5xy + y - 1 - 3

= -8x² + 2xyz + 10xy + y - 4.

N - M = (5x ²+ xyz - 5xy + 3 - y) - (3xyz - 3x² + 5xy - 1)

= 5x² + xyz - 5xy + 3 - y - 3xyz + 3x² - 5xy + 1

= ( 5x² + 3x² ) + xyz - 3xyz - 5xy - 5xy - y + 3 + 1

= 8x² - 2xyz - 10xy - y + 4.

Cho tam giác ABC vuông tại A. Tia phân giác của góc ABC cắt AC tại D, lấy E trên BC sao cho BE=AB

Trên tia đối của tia DE lấy điểm M sao cho. So sánh EC và AM

A. EC<AM

B. EC=AM

C. EC>AM

D. Chưa đủ điều kiện để so sánh

Choose the letter A, B, C or D to complete the passage below

Water pollution happens __________ (6) toxic substances enter water bodies such as lakes, rivers, oceans and so on, getting dissolved in them, lying suspended in the water or depositing on the bed. This degrades the quality of water. Not __________ (7) does this spell disaster for aquatic ecosystems, the pollutants also seep through and reach the groundwater, which might end up in our households as contaminated water we use in our daily activities, including drinking.

Water pollution can be __________ (8) in a number of ways, one of the most polluting being city sewage and industrial waste discharge. Indirect sources __________ (9) water pollution include contaminants that enter the water supply from soils or groundwater systems and from the atmosphere via rain. Soils and groundwater contain __________ (10) residue of human agricultural practices and also improperly disposed of industrial wastes.

Pollutants can be of varying kinds: organic, inorganic, radioactive and so on. In fact, the list of possible water contaminants is just too vast to be listed here.

Question 7:

A. both

B. only

C. well

D. either

f(-2) . f(3) = [ 4a-2b+c.( 9a+3b+c) ]

=( 4a-2b+c ) . [ 13a+b+2c-( 4a-2b+c ) ]

Mà 13a+b+2c = 0 (gt)

=>f(-2) . f(3) =- [(4a-2b+c)²]

Có (4a-2b+c)²luôn ≥ 0 => f(-2) . f(3) ≤ 0

a) Bậc của đa thức là 3

b) Bậc của đa thức là 3

a)

P + Q = x2y + xy2 – 5x2y2 + x3 + 3xy2 – x2y + x2y2

= x3 – 5x2y2 + x2y2 + x2y – x2y + xy2 + 3xy2

= x3 – 4x2y2 + 4xy2

b)

M + N = x3 + xy + y2 – x2y2 – 2 + x2y2 + 5 – y2

= x3 – x2y2 + x2y2 + y2 – y2 + xy - 2 + 5

= x3 + xy + 3.

Read the passage below and decide whether the statements are TRUE or FALSE?

Bowing is nothing less than an art form in Japan, respect pounded into children’s heads from the moment they enter school. For tourists, a simple inclination of the head or an attempt at a bow at the waist will usually suffice. The duration and inclination of the bow is proportionate to the elevation of the person you’re addressing. For example, a friend might get a lightning-fast 30-degree bow; an office superior might get a slow, extended, 70-degree bow. It’s all about position and circumstance.

There is no tipping in any situation in Japan — cabs, restaurants, personal care. To tip someone is actually a little insulting; the services you’ve asked for are covered by the price given, so why pay more? If you are in a large area like Tokyo and can’t speak any Japanese, a waiter or waitress might take the extra money you happen to leave rather than force themselves to deal with the awkward situation of explaining the concept of no tipping in broken English.

Question: The duration and inclination of a bow doesn’t depend on who you greet.

A. True

B. False