Bài nào?

5.

\(A=B\Leftrightarrow\left\{{}\begin{matrix}x-5\ge0\\x+2>0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ge5\\x>-2\end{matrix}\right.\Leftrightarrow x\ge5\)

6.

a, ĐK: \(\left\{{}\begin{matrix}2-\sqrt{x-1}\ge0\\x-1\ge0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\sqrt{x-1}\le2\\x\ge1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\le5\\x\ge1\end{matrix}\right.\Leftrightarrow1\le x\le5\)

b, ĐK: \(\left\{{}\begin{matrix}x-2\ge0\\x-2\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ge2\\x\ne2\end{matrix}\right.\Leftrightarrow x>2\)

c, ĐK: \(\left\{{}\begin{matrix}x^2-4\ge0\\x-2\ge0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne\pm2\\x>2\end{matrix}\right.\Leftrightarrow x>2\)

d, ĐK: \(\left\{{}\begin{matrix}6x-1\ge0\\x+3\ge0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ge\dfrac{1}{6}\\x\ge-3\end{matrix}\right.\Leftrightarrow x\ge\dfrac{1}{6}\)

Tham Khảo

Ex3

 Although there are modern knitting machines, the artisans in my village like using traditional looms

 Many children like to go to Bat Trang Ceramic village as they can make their own pottery there

 We have to follow more than ten stages so that we can make a simple conical hat

 Sinh paintings are special since they are burned after worship

a)

=15(can6-1)/(6-1)+4/(4-2)-12/(3-4)

=3(can6-1)+2+12

=3\(\sqrt{6}\)-3+2+12

=17+3can6

các câu còn lại tương tự liên hợp mẫu 

c: Ta có: \(\dfrac{3+2\sqrt{3}}{\sqrt{3}}+\dfrac{2+\sqrt{2}}{\sqrt{2}+1}-\left(2+\sqrt{3}\right)\)

\(=2+\sqrt{3}+\sqrt{2}-2-\sqrt{3}\)

\(=\sqrt{2}\)

1 hadn't seen - were

2 doesn't like - being phoned

3 is eaten

4 is leaving - will wait

5 won't be - will you go

6 is coming - don't want

7 hasn't read - have gone

8 haven't seen - left

9 was washing - was writing

10 sets - goes

11 were talking - walked

12 has stayed - studied - was

13 was made

14 had told - went away

15 will be held

16 had gone - sat - rested

17 watched - had done

1 is grown in many countries in the world

2 was invented by Graham bell many years ago

3 has been used for many years

4 Is English practiced by Lan everyday

5 will be taken out of the city 

6 can this letter be sent by Mary 2 days ago

7 is being made from vegetables

8 must be finished before Sunday

9 hadn't been used for a long time

10 Will I be met at the airport by Jack tomorrow

12 It is thought that Maradona is.....

13 It has been believed that the job is.....

14 It was explained that this powerful.....

1 was arrested before the garden by the boy yesterday

2 his cats taken care of carefully by Jack everyday

3 Has the country been protected from Covid-19 successfully

4 is reported that the man is running out of money

is reported to be running out of money\

5 has been said that the thief got out of the prison

has been said to have got out of the prison

6 was thought that Mary had turned down the job

Mary was thought to have  turned down the job

\(1,\\ a,=\dfrac{\left(3+2\sqrt{3}\right)\sqrt{3}}{3}+\dfrac{\left(2+\sqrt{2}\right)\left(\sqrt{2}-1\right)}{1}\\ =\dfrac{3\sqrt{3}+6}{3}+\sqrt{2}=\sqrt{3}+1+\sqrt{2}\\ b,=\left(\dfrac{\sqrt{5}+\sqrt{2}}{3}-\dfrac{\sqrt{5}-\sqrt{2}}{3}+1\right)\cdot\dfrac{1}{\left(\sqrt{2}+1\right)^2}\\ =\dfrac{\sqrt{5}+\sqrt{2}-\sqrt{5}+\sqrt{2}+3}{3}\cdot\dfrac{1}{\left(\sqrt{2}+1\right)^2}\\ =\dfrac{2\sqrt{2}+3}{3\left(3+2\sqrt{2}\right)}=\dfrac{1}{3}\)

\(2,\\ A=2x+\sqrt{\left(x-3\right)^2}=2x+\left|x-3\right|\\ =2\left(-5\right)+\left|-5-3\right|=-10+8=-2\\ B=\dfrac{\sqrt{\left(2x+1\right)^2}}{\left(x-4\right)\left(x+4\right)}\left(x-4\right)^2=\dfrac{\left|2x+1\right|\left(x-4\right)}{x+4}\\ B=\dfrac{17\cdot4}{12}=\dfrac{17}{3}\)

Câu 1:

PTHH: 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂

PTHH: Na₂O + H₂SO₄ → Na₂SO₄ + H₂O

PTHH: Cu(OH)₂ + H₂SO₄ → CuSO₄ + 2H₂O

Câu 2:

a, \(n_{H_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)

PTHH: Fe + H₂SO₄ → FeSO₄ + H₂

Mol:     0,2     0,2                            0,2

b, \(m_{Fe}=0,2.56=11,2\left(g\right)\)

c, \(C_{M_{ddH_2SO_4}}=\dfrac{0,2}{0,1}=2M\)