`a, -x = -17 - 8`
`-x = -25`
`x = 25`
`b, 35 - x = 37`
`x = 35 - 37`
`x= -2`
`c, -19 - x = -20`
`x = 20-19`
`x = 1`
Bazo | Tên |
$Fe(OH)_3$ | Sắt III hidroxit |
$Ca(OH)_2$ | Canxi hidroxit |
Oxit trung tính | Tên |
$CO$ | Cacbon oxit |
Muối | Tên |
$MgSO_4$ | Magie sunfat |
$Ba(HCO_3)_2$ | Bari hidrocacbonat |
$ZnSO_3$ | Kẽm sunfit |
$FeSO_4$ | Sắt II sunfat |
$NaHSO_4$ | Natri hidrosunfat |
$Cr(NO_3)_3$ | Crom III nitrat |
Oxit bazo | Tên |
$CuO$ | Đồng II oxit |
$FeO$ | Sắt II oxit |
Axit | Tên |
$HCl$ | Axit clohidric |
$H_3PO_4$ | Axit photphoric |
Oxit axit | Tên |
$SO_3$ | Lưu huỳnh trioxit |
24. B
25. A
26. B
27. B
28. D
29. C
30. C
31. A?
32. B
33. A
34. A
35. A
24. B
25. A
26. A
27. D
28. D
29. C
30. C
31. D
32. B
33. D
34. A
• A
\(\left(3-\dfrac{1}{2}\right)x=13\\ \left(\dfrac{6-1}{2}\right)x=13\\ \dfrac{5}{2}x=13\\ x=13:\dfrac{5}{2}\\ x=\dfrac{26}{5}\)
a) \(sin^2\alpha\cdot cos^2\alpha=\left(sin\alpha\cdot cos\alpha\right)^2=\left[\dfrac{1}{2}sin\left(2\alpha\right)\right]^2=\dfrac{1}{4}sin^2\left(2\alpha\right)\)
b) \(\dfrac{cos\left(\alpha-\beta\right)}{sin\alpha\cdot sin\beta}=\dfrac{cos\alpha\cdot cos\beta+sin\alpha\cdot sin\beta}{sin\alpha\cdot sin\beta}=\dfrac{cos\alpha\cdot cos\beta}{sin\alpha\cdot sin\beta}+\dfrac{sin\alpha\cdot sin\beta}{sin\alpha\cdot sin\beta}=\dfrac{1}{tg\alpha\cdot tg\beta}+1\)
c) \(cos^2\alpha\left(tg^2\alpha+1\right)=cos^2\alpha\cdot tg^2\alpha+cos^2\alpha=sin^2\alpha+cos^2\alpha=1\)
d) \(tg\alpha+1=\dfrac{sin\alpha}{cos\alpha}+1=\dfrac{sin\alpha}{cos\alpha}+\dfrac{cos\alpha}{cos\alpha}=\dfrac{sin\alpha+cos\alpha}{cos\alpha}\)