#h24cfs_592 "Không có ý gì" thế đằng trước là gì vậy? Bị vô tri cái nói vô duyên vậy hả? 

\(k)\left(-2\right)^3\cdot\dfrac{-1}{24}+\left(\dfrac{4}{5}-1,2\right):\dfrac{2}{15}\\ =-8\cdot\dfrac{-1}{24}+\left(\dfrac{4}{5}-\dfrac{6}{5}\right)\cdot\dfrac{15}{2}\\ =\dfrac{\left(-8\right)\cdot\left(-1\right)}{24}+\dfrac{-2}{5}\cdot\dfrac{15}{2}\\ =\dfrac{1}{3}+\left(-3\right)\\ =\dfrac{1}{3}-\dfrac{9}{3}\\ =-\dfrac{8}{3}\)

\(l)25\%-1\dfrac{1}{2}-\left(-\dfrac{1}{2}\right)^2+0,25:\dfrac{1}{12}\\ =\dfrac{1}{4}-\dfrac{3}{2}-\dfrac{1}{4}+\dfrac{1}{4}\cdot\dfrac{12}{1}\\ =\dfrac{1}{4}-\dfrac{6}{4}-\dfrac{1}{4}+3\\ =-\dfrac{3}{2}+\dfrac{6}{2}\\ =\dfrac{3}{2}\)

\(m)\left(\dfrac{-2}{5}\right)^2+\dfrac{1}{2}\cdot\left(4,5-2\right)-50\%\\ =\dfrac{4}{25}+\dfrac{1}{2}\cdot\left(\dfrac{9}{2}-\dfrac{4}{2}\right)-\dfrac{1}{2}\\ =\dfrac{4}{25}+\dfrac{5}{4}-\dfrac{1}{2}\\ =\dfrac{16}{100}+\dfrac{125}{100}-\dfrac{50}{100}\\ =\dfrac{91}{100}.\)

`3/2 -x = 4/9`

`x = 3/2 - 4/9`

`x= 19/18`.

`14.` Chọn A. /d/, còn lại là /t/

`15.` Chọn D. /d/, còn lại là /t/

`16.` Chọn D. /e/, còn lại là /i:/

`17.` Chọn B. /a:/, còn lại lại là /ae/.

IX. Write conditional sentences type 2, using the cues given.

1. What/ happen/ if/ water pollution/ stop?

`->` What would happen if water pollution stopped?

2. We/ be/ happy/ if/ air pollution/ the world/ be/ a/ better place?

`->` Would we be happy if air pollution in the world were a better place?

3. If/ there/ be/ no more pollution/ the world/ be/ a better place?

`->` Would the world would be a better place if there were no more pollution?

4. If/I/ be/ you/I/ take/ these bottles/ the bottle bank.

`->` If I were you, I would take these bottles to the bottle bank.

5. If/ people/ not really care/ the environment/ they/ not try/ save it.

`->`If people didn't really care the environmet, they wounld not try to save it.

6. The river/ not be/ so polluted/ if/ factories/ not dump/ waste/ it.

`->` The river wouldn't be so polluted if factories didn't dump waste into it.

7. We/ be/ less worried/ if/ oil spills/ not have/ such destructive effects.

`->` We would be less worrried if oild spills didn't have such destructive effects.

_

`-` Công thức: If + S + `V_{QKĐ}`, S + would/could + `V_1`

`*` trong đó: `V_{QKĐ}` gồm:

`+` didn't + `V_1` 

`+` `V_{2//ed}`

`+` were. 

VII. Complete the sentences with the verbs in brackets. Use conditional sentences type 1.

1. gets

2. will not be

3. keep

4. will help

5. don't stop, will become

6. recycle - will not produce

7. will have - dump

8. continues - will rise

9. keeps - will not be

10. will threaten - don't cut down

_ 

`-` Công thức: If + S + `V_{HTĐ}`, S + will/can + `V_1`

`*` trong đó: `V_{HTĐ}` gồm:

`+` don't/doesn't + `V_1` 

`+` `V_{1//s//es}`

`+` am/is/are.

`*` Bài 2.

Gọi `x` là chiều dài của mảnh vườn đó

       `y` là chiều rộng của mảnh vườn đó 

`(m;x,y>0)`

`-` Vì mảnh vườn hình chữ nhật có chu vi `56m` nên:

`(x+y)*2=56` `=>2x+2y=56`     `(1)`

`-` Vì nếu tăng chiều dài `4m` và giảm chiều rộng `2m` thì diện tích tăng `8m^2` nên:

`(x+4)(y-2)=xy-8`

`=> xy -2x +4y - 8 =xy-8`

`=> xy -2x+4y-xy = -8+8`

`=> -2x+4y=0`     `(2)`

Từ `(1)` và `(2)`, ta có hệ phương trình: \(\left\{{}\begin{matrix}2x+2y=56\\-2x+4y=0\end{matrix}\right.\)

Giải hệ phương trình, ta được: \(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{56}{3}\\y=\dfrac{28}{3}\end{matrix}\right.\left(nhận\right)\)

Vậy, chiều dài của mảnh vườn đó là `56/3 m`.

VIII. Complete the sentences with the verbs in brackets. Use conditional sentences type 2.

1. weren't

2. would decrease

3. didn't dump

4. would be

5. bought

6. didn't bury - wouldn't pollute 

7. wouldn't be - cared

8. would happen - were

9. paid - would be 

10. polluted - would soon become

_

`-` Công thức: If + S + `V_{QKĐ}`, S + would/could + `V_1`

`*` trong đó: `V_{QKĐ}` gồm:

`+` didn't + `V_1` 

`+` `V_{2//ed}`

`+` were. 

Tỉ số đồng dạng từ tam giác đồng dạng nha.

`-` Vì `d=2f` nên ảnh thật, ngược chiều và bằng vật.