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18 tháng 12 2021

Giúp mình với

28 tháng 12 2021

PTHH: \(Zn+2HCl\rightarrow ZnCl_2+H_2\uparrow\)

            \(FeO+H_2\xrightarrow[]{t^o}Fe+H_2O\)

Ta có: \(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)=n_{H_2}=n_{Fe}\) \(\Rightarrow m_{Fe}=0,1\cdot56=5,6\left(g\right)\)

 

8 tháng 10 2021

1 How long do you live in HN

2 How often did you go to the movies

3 What did Mrs Robinson buy

4 When was your father in Nghe An

5 How do they go to school

6 Why didn't she go to class

7 Who left home at 7o'clock yesterday

8 What subject does he study in the high school

9 What is your favorite hobby

10 How far is it

8 tháng 10 2021

cảm mơn nhìuu ạ:33

8 tháng 9 2021

a/ \(\left(x-3\right)^2+6\left(x-3\right)+9\)

\(=\left(x-3\right)^2+2.\left(x-3\right).3+3^2\)

\(=\left(x-3+3\right)^2=x^2\)

==========

b/ \(\left(x+2021\right)^2+2\left(x+2021\right)\left(x-2021\right)+\left(x-2021\right)^2\)

\(=\left(x+2021+x-2021\right)^2=4x^2\)

===========

c/ \(2022^2-2.2021.2022+2021^2\)

\(=\left(2022-2021\right)^2=1\)

==========

d/ \(\left(x+44\right)^2-88\left(x+44\right)+1936\)

\(=\left(x+44\right)^2-2.\left(x+44\right).44+44^2\)

\(=\left(x+44-44\right)^2=x^2\)

d: Ta có: \(\left(x+44\right)^2-88\left(x+44\right)+1936\)

\(=\left(x+44-44\right)^2\)

\(=x^2\)

6 tháng 11 2021

1. commuity service is work done by a person or group of people that benifits others

2. it is often done near the area where you live , so your own community gets the benifits work

3. no

4. community service can help many difference group of people , even animal and the inviroment 

5. community service is often organized through a local group , such as a place of worship , school , or non- profit organization , or you can start your own community service project .

6.community service can even involve raising funds by donating used goods or selling used goods like clothing 

10 tháng 11 2021

dài vãi

10 tháng 11 2021

Huhu cứu vớiii

10 tháng 11 2021

quá dài

17 tháng 3 2022

\(\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+...+\dfrac{1}{13.15}\right).x=\dfrac{-26}{45}\\ \Leftrightarrow\left(\dfrac{2}{1.3}+\dfrac{2}{3.5}+...+\dfrac{2}{13.15}\right).x=\dfrac{-52}{45}\\ \Leftrightarrow\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{13}-\dfrac{1}{15}\right).x=\dfrac{-52}{45}\\ \Leftrightarrow\left(1-\dfrac{1}{15}\right).x=\dfrac{-52}{45}\\ \Leftrightarrow\dfrac{14}{15}.x=\dfrac{-52}{45}\\ \Leftrightarrow x=-\dfrac{26}{21}\)

17 tháng 3 2022

(11.3+13.5+...+113.15).x=−2645⇔(21.3+23.5+...+213.15).x=−5245⇔(1−13+13−15+...+113−115).x=−5245⇔(1−115).x=−5245⇔1415.x=−5245⇔x=−2621