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NM
3 tháng 12 2021

gọi m (g) là khối lượng dung dịch ban đầu

khối lượng H2SO4 ban đầu là : \(61,25\%\times m=0,6125m\left(g\right)\)

Khối lượng H2SO4 lúc sau là : \(0,6125m+40\times\frac{98}{80}=0,6125m+49\)

vậy ta có phương trình : \(\frac{0,6125m+49}{m+40}=73,5\%\Leftrightarrow m=160g\)

1 tháng 8 2019
Cho mik sửa tí Cái phần b ý là chứng tỏ góc tOm là góc vuông nhé ko phải là góc tù là góc vuông đâu
1 tháng 8 2019

Mình có 2 cách nhé!

C1 : Bấm log(5100) = 69,89700043 \(\approx\)70

C2 : Bấm 5100 = 7,888609052 . 1069 

=> 69 + 1 = 70

Vậy 5100 có 70 chữ số trong hệ thập phân

Mình làm theo cảm tính

10 tháng 8 2019

Gọi 5100có n chữ số (n thuộc N*)

Vì 2100 có 31 chữ số nên ta có:

1030<2100<1031                        (1)

Vì 5100có n chữ số nên ta có:

10n-1<2100<10n

Từ (1),(2),suy ra:

1030.10n-1<2100.5100<1031.10n

Suy ra:1030+n-1<10100<1031+n

Suy ra:1029+n10100<1031+n

Suy ra:29+n<100<31+n

Suy ra:100=n+30

Suy ra:n=70

Vậy 5100 có 70 chữ số

1 tháng 8 2019

a) \(\frac{5^5.20^3-5^4.20^3+5^7.4^5}{\left(20+5\right)^3.4^5}\)

\(\frac{5^5.\left(2^2.5\right)^3-5^4.\left(2^2.5\right)^3+5^7.\left(2^2\right)^5}{\left(5^2\right)^3.\left(2^2\right)^5}\)

\(\frac{5^5.2^6.5^3-5^4.2^6.5^3+5^7.2^{10}}{5^6.2^{10}}\)

\(\frac{5^8.2^6-5^7.2^6+5^7.2^{10}}{5^6.2^{10}}\)

\(\frac{5^7.2^6.\left(5-1+2^4\right)}{5^6.2^{10}}\)

\(\frac{5.20}{2^4}=\frac{25}{4}\)

2 tháng 8 2019

\(\frac{4^6\cdot9^5+6^9\cdot120}{8^4\cdot3^{12}-6^{11}}\)

\(=\frac{2^{12}\cdot3^{10}+2^3\cdot3\cdot5\cdot2^9\cdot3^9}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}\)

\(=\frac{2^{12}\cdot3^{10}+2^{12}\cdot3^{10}\cdot5}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}\)

\(=\frac{2^{12}\cdot3^{10}\left(1+5\right)}{2^{11}\cdot3^{11}\left(6-1\right)}\)

\(=\frac{2^{13}\cdot3^{11}}{2^{11}\cdot3^{11}\cdot5}=\frac{2^2}{5}=\frac{4}{5}\)

1) Fill in there is / there are / there isn't / there aren't.1)_____________ a beautiful garden in front of our house.2) ____________ some pencils on the desk.3)_____________ any bananas in the fridge.4)_____________ any milk in the bottle.5)_____________ a swimming pool in your neighborhood.6)_____________ any farmous streets in your town ?7)____________ a lamp on the coffee ctabe ?8)____________ some paintings on the wall.9)____________ a wardrobe next to the sofa.10)___________ any flowers...
Đọc tiếp

1) Fill in there is / there are / there isn't / there aren't.

1)_____________ a beautiful garden in front of our house.

2) ____________ some pencils on the desk.

3)_____________ any bananas in the fridge.

4)_____________ any milk in the bottle.

5)_____________ a swimming pool in your neighborhood.

6)_____________ any farmous streets in your town ?

7)____________ a lamp on the coffee ctabe ?

8)____________ some paintings on the wall.

9)____________ a wardrobe next to the sofa.

10)___________ any flowers in the vase.

2) Fill in the gaps with possessive pronoun or adjective.

1) This is John and this is_________________brother.

2) This is Mary's car. It's_________________________.

3) Your house is big but_________________is small.

4) You can have this book. It's___________________?_.

5) This is MMike._______________parents are kind and generous.

6) I love___________________family. They are wonderful.

7) Julie and Ann are sisters._________________surname is Fox.

8) Is she_______________sister ? No, he hasn't got a sister.

9) Whose book is this ? It's_____________. Thank you.

10) Their car is expensive but__________________is cheap.

 

4

1) Fill in there is / there are / there isn't / there aren't.

1)______There is_______ a beautiful garden in front of our house.

2) ______There are______ some pencils on the desk.

3)______There aren't_______ any bananas in the fridge.

4)______There isn't_______ any milk in the bottle.

5)_______There is______ a swimming pool in your neighborhood.

6)________there aren' t _____ any farmous streets in your town ?

7)_____There isn't_______ a lamp on the coffee ctabe ?

8)______there are ______ some paintings on the wall.

9)_____There is _______ a wardrobe next to the sofa.

10)______There isn't_____ any flowers in the vase.

Study well 

1 tháng 8 2019

1) Fill in there is / there are / there isn't / there aren't.

1)______There is_______ a beautiful garden in front of our house.

2) ______There are______ some pencils on the desk.

3)______There aren't_______ any bananas in the fridge.

4)______There isn't_______ any milk in the bottle.

5)_______There is______ a swimming pool in your neighborhood.

6)________there aren' t _____ any farmous streets in your town ?

7)_____There isn't_______ a lamp on the coffee ctabe ?

8)______there are ______ some paintings on the wall.

9)_____There is _______ a wardrobe next to the sofa.

10)______There isn't_____ any flowers in the vase.

1 tháng 8 2019

Số lớn nhất có hai chữ số là 99

Số nhỏ nhất có hai chữ số là 10

Số thứ hai là:

99 - 10 = 89 

Đ/s: 89

2 tháng 8 2019

số lớn nhất có hai chữ số là 99

số bé nhất có hai chữ số là 10

số thứ hai là:

99-10=89
Đ/S:89

1 tháng 8 2019

Câu hỏi của Hiền Nguyễn Thị