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a) Khối lượng của quả cầu nhôm là:

m=V.D= 0,004 . 2700=10,8 (kg)

b) Trọng lượng của quả cầu nhôm là:

P=10.m= 10 . 10,8= 108 (N)

c) Trọng lượng riêng của quả cầu nhôm là:

d=P:V= 108:0,004 = 27000 (N/m khối)

Đ/S : a 10,8kg

b 108 N

c 27000 N/ m khối

vì |x+2| và |y-1|> hoặc bằng 0 mà |x+2|+|y-1|=0

suy ra x+2=0 và y-1=0 vậy x=-2,;y=1

Due to the fact that the demand for tea was very high in the 19th century, its price increased much.

A. It was not until the 19th century that the demand for tea started to increase.

B. In the 19th century the price for tea didn’t increase despite the demand.

C. The demand for tea was so high in the 19th century that its price increased much.

D. It was its price that decreased the demand for tea in the 19th century.

đề đúng   
 

1/2 = 0,5

3/4 = 0,75

20/8= 2,5

Tick cho mik nhé