Ta có : 

\(\frac{x}{5}=\frac{y}{4}\Rightarrow\frac{x}{35}=\frac{y}{28}\)

\(\frac{y}{7}=\frac{z}{8}\Rightarrow\frac{y}{28}=\frac{z}{32}\)

Do đó : 

\(\frac{x}{35}=\frac{y}{28}=\frac{z}{32}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có : 

\(\frac{x}{35}=\frac{y}{28}=\frac{z}{32}=\frac{x-y+z}{35-28+32}=\frac{7}{39}\)

... tự làm tiếp nhé 

\(\frac{x}{5}=\frac{y}{4}\Leftrightarrow\frac{x}{35}=\frac{y}{28},\frac{y}{7}=\frac{z}{8}\Leftrightarrow\frac{y}{28}=\frac{z}{32}\)

suy ra \(\frac{x}{35}=\frac{y}{28}=\frac{z}{32}\).

Áp dụng tính chất dãy tỉ số bằng nhau ta có: 

\(\frac{x}{35}=\frac{y}{28}=\frac{z}{32}=\frac{x-y}{35-28}=\frac{7}{7}=1\)

\(\Leftrightarrow\hept{\begin{cases}x=1.35=35\\y=1.28=28\\z=1.32=32\end{cases}}\)

a) Dễ thấy \(\widehat{A_4}=\widehat{B_3}\left(=52^{\text{o}}\right)\)

=> m // n (2 góc so le trong bằng nhau)

b) Vì m//n => \(\widehat{A_1}=\widehat{B_2}=\widehat{A_3}\text{ ; }\widehat{A_2}=\widehat{B_1}=\widehat{B_3}\)

mà \(\widehat{B_3}=52^{\text{o}}\Rightarrow\widehat{A_2}=\widehat{B_1}=52^{\text{o}}\)

lại có \(\widehat{B_2}+\widehat{B_3}=180^{\text{o}}\Rightarrow\widehat{B_2}=180^{\text{o}}-\widehat{B_3}=180^{\text{o}}-52^{\text{o}}=128^{\text{o}}\)

=> \(\widehat{A_1}=\widehat{B_2}=\widehat{A_3}=128^{\text{o}}\)

a) Có A4 = B3 (=52 độ) mà chúng là 2 góc so le trong)=> m//n (dhnb 2 đường thẳng song song)

b) +) B2 = ?

Có m//n (CMT) => A4 + B2 = 180 độ ( 2 góc trong cùng phía) => B2 = 180 độ - 52 độ = 128 độ

+) A1 = ?

Có m//n (CMT) => B2 = A1 (2 góc đồng vị) mà B2 = 128 độ => A1 = 128 độ 

+) A2 =?

Có m//n (CMT) => A2 = B3 (2 góc đồng vị) mà B3 = 52 độ => A2 = 52 độ

+)B1 = ?

Có m//n (CMT) => A4 = B1 (2 góc đồng vị) mà A4 = 52 độ => B1 = 52 độ

+) A3 = ?

Có m//n (CMT) => A3 + B3 = 180 độ (2 góc trong cùng phía) => A3 + 52 độ = 180 độ => A3 = 180 độ - 52 độ = 128 độ

+) B4 = ?

Có m//n (CMT) => A3 = B4 (2 góc đồng vị) mà A3 = 128 độ => B4 = 128 độ

là seo?

mã đăng nhập fb

12.   The car drove ______just outside Winchester.

        A. away                 B. off                       C. down                   D. in

13.   Talks ______last week over the issue of overtime pay.

        A. broke in             B. broke down          C. broke off              D. broke away

14.   As the funeral service began, Frances ______and cried.

        A. broke down        B. broke off              C. broke in               D. broke away

15.   Dad would occasionally ______with an amusing comment.

        A. broke off            B. broke out              C. broke up               D. break in

16.   Someone had ______through the bedroom window.

        A. broken up           B. broken off            C. broken down        D. broken in

17.   Did you know they’ve ______their engagement?

        A. broken off          B. broken in              C. broken down        D. broken out

18.   The fire must have ______during the night.

        A. broke off            B. brought in.           C. broken out            D. brought down

19.   There were suggestions that her involvement had ______the partnership.

        A. broken off          B. broken up             C. broken about        D. brought in

20.   When do you ______for Easter?

        A. break away        B. break down          C. break up               D. break in

TL:

20.   When do you ______for Easter?

        A. break away        B. break down          C. break up               D. break in

o l m . v n

Tiếng anh lớp 7

1 

Dương Thanh Huyền  CTV

1 giờ trước (12:05)

12.   The car drove ______just outside Winchester.

        A. away                 B. off                       C. down                   D. in

13.   Talks ______last week over the issue of overtime pay.

        A. broke in             B. broke down          C. broke off              D. broke away

14.   As the funeral service began, Frances ______and cried.

        A. broke down        B. broke off              C. broke in               D. broke away

15.   Dad would occasionally ______with an amusing comment.

        A. broke off            B. broke out              C. broke up               D. break in

16.   Someone had ______through the bedroom window.

        A. broken up           B. broken off            C. broken down        D. broken in

17.   Did you know they’ve ______their engagement?

        A. broken off          B. broken in              C. broken down        D. broken out

18.   The fire must have ______during the night.

        A. broke off            B. brought in.           C. broken out            D. brought down

19.   There were suggestions that her involvement had ______the partnership.

        A. broken off          B. broken up             C. broken about        D. brought in

20.   When do you ______for Easter?

        A. break away        B. break down          C. break up               D. break in

^H^T

Tại sao động vật không có khả năng tự dưỡng?

TL

Vì thức ăn của động vật là thịt động vật, nó phải đi tìm mồi, săn mồi thì mới có thịt ăn

HT

vì ????????????????????????????????????????????????????????????????

TL

= 5/2-563/165-4/3+1/3(1/2+1/2-7/2)

=5/2-563/165-4/3+1/3.-5/2=-508/165

Hok tốt

\(2\frac{1}{2}-3,4\left(12\right)-\frac{4}{3}+\frac{1}{3}\left(\frac{1}{2}+0,5-3\frac{1}{2}\right)\)

\(=\frac{5}{2}-\left(\frac{17}{5}+\frac{2}{165}\right)-\frac{4}{3}-\frac{5}{6}\)

\(=\frac{5}{2}-\frac{17}{5}-\frac{2}{165}-\frac{4}{3}-\frac{5}{6}=-\frac{508}{165}\)

1.SKATING

2. PLAYING

3. COLLECTING

3. I really love  (skate) skating in the park with my friends.

4. He dislik.e (play) playing board games because he loses all the time.

5. My friend, Lily, is interested in  (collect)collecting  plas bottles to recycle.

\(2\frac{1}{2}.3,4\left(12\right)-\frac{4}{3}+\frac{1}{3}.\left(\frac{1}{2}+0,5-3\frac{1}{2}\right)\)

\(=\frac{5}{2}.\frac{563}{33}-\frac{4}{3}+\frac{1}{3}.\left(\frac{1}{2}+\frac{1}{2}-\frac{7}{2}\right)\)

\(=\frac{2815}{66}-\frac{4}{3}+\frac{1}{3}.\frac{-5}{2}\)

\(=\frac{909}{22}+\frac{-5}{6}\)\(=453\frac{2}{3}\)

\(2\frac{1}{2}.3,4\left(12\right)-\frac{4}{3}+\frac{1}{3}\left(\frac{1}{2}+0,5-3\frac{1}{2}\right)\)

= \(\frac{5}{2}.\left(3,4+\frac{2}{165}\right)-\frac{4}{3}+\frac{1}{3}\left(-\frac{5}{2}\right)\)

= \(\frac{5}{2}\left(\frac{17}{5}+\frac{2}{165}\right)-\frac{4}{3}-\frac{5}{6}\)

\(=\frac{17}{2}+\frac{1}{33}-\frac{4}{3}-\frac{5}{6}\)

\(=\frac{561}{66}+\frac{2}{66}-\frac{88}{66}-\frac{55}{66}=\frac{70}{11}\)