Uh mình chỉ giúp được câu a

\(x^2-5x+3=0\)

\(\Delta=b^2-4ac\)

\(=\left(-5\right)^2-4.1.3\)

\(=25-12=13>0\)

\(x1=\dfrac{b+\sqrt{\Delta}}{2a}=\dfrac{5+\sqrt{13}}{2}\)

\(x2=\dfrac{b-\sqrt{\Delta}}{2a}=\dfrac{5-\sqrt{13}}{2}\)

mk ko bik ahihi

\(4Al + 3O_2 \xrightarrow{t^o} 2Al_2O_3\\ 2Al + 3Cl_2 \xrightarrow{t^o} 2AlCl_3\\ Al_2O_3 + 6HCl \to 2AlCl_3 + 3H_2O\\ Al_2O_3 + 3H_2SO_4 \to Al_2(SO_4)_3 + 3H_2O\\ AlCl_3 + 3AgNO_3 \to 3AgCl + Al(NO_3)_3\\ Al_2(SO_4)_3 + 3Ba(NO_3)_2 \to Al(NO_3)_2 + 3BaSO_4\\ Al_2(SO_4)_3 + 6KOH \to 2Al(OH)_3 + 3K_2SO_4\\ Al(NO_3)_3 + 3KOH \to Al(OH)_3 + 3KNO_3\\ Al(OH)_3 + NaOH \to NaAlO_2 + 2H_2O\\ 2Al(OH)_3 \xrightarrow{t^o} Al_2O_3 + 3H_2O\)

4Al + 3O2 -> 2Al2O3

Al2O3 + 6HCl -> 2AlCl3 + 3H2O

2Al + 6HCl -> 2AlCl3 + 3H2

Al2O3 + 3H2SO4 -> Al2(SO4)3 + 3H2O

AlCl3 + 3AgNO3 -> Al(NO3)3 + 3AgCl

Al2(SO4)3 + 3Ba(NO3)2 -> 2Al(NO3)3 + 3BaSO4

Al(NO3)3 + 3NaOHvừa đủ -> Al(OH)3 + 3NaNO3

Al2(SO4)3 + 3Ba(OH)2vừa đủ -> 2Al(OH)3 + 3BaSO4

Al(OH)3 + NaOH -> NaAlO2 + 2H2O

2Al(OH)3 -> Al2O3 + 3H2O

Al2O3 + 2NaOH -> 2NaAlO2 + H2O
 

\(4Al+3O_2\underrightarrow{^{t^0}}2Al_2O_3\)

\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

\(Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\)

\(Al_2O_3+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)

\(AlCl_3+3AgNO_3\rightarrow Al\left(NO_3\right)_3+3AgCl\)

\(Al_2\left(SO_4\right)_3+3Ba\left(NO_3\right)_2\rightarrow2Al\left(NO_3\right)_3+3BaSO_4\)

\(Al_2\left(SO_4\right)_3+6NaOH\rightarrow2Al\left(OH\right)_3+2Na_2SO_4\)

\(Al\left(NO_3\right)_3+3NaOH\rightarrow Al\left(OH\right)_3+3NaNO_3\)

\(NaOH+Al\left(OH\right)_3\rightarrow NaAlO_2+2H_2O\)

\(2Al\left(OH\right)_3\underrightarrow{^{t^0}}Al_2O_3+3H_2O\)

\(2NaOH+Al_2O_3\rightarrow2NaAlO_2+H_2O\)

1 A

2 B

3 A

4 A

5 A

6 C

7 D

8 B

mờ quá mình ko đọc đc

41. These books are her

42. My brother is running very fast

43. you say: "Nam will put his feet on the sofa"

44. VTV3 has a lot of interesting programs

45. Because I played sport; so I didn't have any class yesterday

46. What kind of TV programme do you like

47. Many girls and women do aerobics to keep fit

48. We didn't play video game last night

49. She loves French food so she goes that French restaurant every week

50. How often do you go swimming?