A O C B 1 ? m n 1

Vì Ô là góc vuông của ∆OBC

\(\Rightarrow\widehat{B_1}+\widehat{C_1}=90^o\)mà \(\widehat{C_1}=60^o\)

\(\Rightarrow\widehat{B_1}+60^o=90^o\)

\(\Rightarrow\widehat{B_1}=30^o\)

BÀi 2 :

a) Vì | x + 1,5 | ≥ 0 ∀ x 

=> A = | x + 1,5 | - 8 ≥ -8 ∀ x

Dấu " = " xảy ra <=> x + 1,5 = 0 <=> x = -1,5

Vậy giá trị nhỏ nhất của A là -8 khi x = -1,5

b) Vì | 2x - 4 | ≥ 0 ∀ x

\(\Rightarrow A=\left|2x-4\right|-\frac{9}{10}\ge-\frac{9}{10},\forall x\)

Dấu "=" xảy ra <=> 2x - 4 = 0 <=> 2x = 4 <=> x = 2

Vậy giá trị nhỏ nhất của B là \(-\frac{9}{10}\) khi x = 2

c) Vì | x - 3,5 | ≥ 0 ∀ x 

=> C = 2,5 - | x - 3,5 | ≤ 2,5

Dấu "=" xảy ra <=> x - 3,5 = 0 <=> x = 3,5

Vậy giá trị lớn nhất của C là 3,5 khi x = 3,5

d) Vì | 5x + 3 | ≥ 0 ∀ x

\(\Rightarrow D=4-\left|5x+3\right|\le4,\forall x\)

Dấu "=" xảy ra <=> 5x + 3 = 0 <=> 5x = -3 <=> \(x=\frac{-3}{5}\)

Vậy giá trị lớn nhất của D là 4 khi \(x=\frac{-3}{5}\)

e) Vì | x - 2 | ≥ 0 ∀ x 

=> | x - 2 | + 3 ≥ 3 ∀ x

\(\Rightarrow E=\frac{1}{\left|x-2\right|+3}\le\frac{1}{3},\forall x\)

Dấu " = " xảy ra <=> x - 2 = 0 <=> x = 2

Vậy giá trị nhỏ nhất của E là \(\frac{1}{3}\)khi x = 2

Câu 13 :

a) 100 . ( 0,1 )3 - 10 . ( 0,1 )2 - ( 0,1 )1 + ( 0,1 )0

\(=100.\left(\frac{1}{10}\right)^3-10.\left(\frac{1}{10}\right)^2-\left(\frac{1}{10}\right)^1+1\)

\(=100.\frac{1}{1000}-10.\frac{1}{100}-\frac{1}{10}+1\)

\(=\frac{1}{10}-\frac{1}{10}-\frac{1}{10}+1\)

\(=1-\frac{1}{10}=\frac{9}{10}\)

b) \(\frac{7}{3}:\frac{11}{2}+\frac{7}{3}:\frac{11}{24}-\frac{7}{3}\)

\(=\frac{7}{3}.\frac{2}{11}+\frac{7}{3}.\frac{24}{11}-\frac{7}{3}\)

\(=\frac{7}{3}.\left(\frac{2}{11}+\frac{24}{11}-1\right)\)

\(=\frac{7}{3}.\frac{15}{11}=\frac{35}{11}\)

Câu 14 :

a) \(\frac{3}{2}.\left(x-\frac{1}{2}\right)-\frac{5}{4}=\frac{1}{4}\)

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

\(=x-\frac{1}{2}=1\)\(=x=\frac{3}{2}\)

b) | 0,81 - x | - 7,7 = 2,3

=> | 0,81 - x | = 2,3 + 7,7 = 10

\(\Rightarrow\orbr{\begin{cases}0,81-x=10\\0,81-x=-10\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0,81-10\\x=0,81-\left(-10\right)\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-9,19\\x=10,81\end{cases}}\)

giúp mk câu b thôi câu a mk lm r

1.   A. generation                  B. goose                     C. ginger                    D. engineer

2.   A. question                      B. mosquito               C. mosque                  D. unique

3.   A. mechanic                    B. stomachache        C. Christmas              D. chance

4.   A. giggle                          B. gone                       C. engine                   D. forget

5.   A. complete                     B. compass                C. concert                  D. century

UNIT 4: Sounds /ʃ/ & /ʒ/

1.   A. chemical                     B. delicious               C. especially             D. musician

2.   A. machine                      B. chef                        C. check                     D. sugar

3.   A. generation                  B. question                C. competition          D. portion

4.   A. unusual                       B. pleasure                C. pleasant                 D. leisure

5.   A. conversation              B. discussion             C. decision                D. mission

UNIT 5: Sounds /ɒ/ & /ɔ:/

1.   A. naughty                       B. floor                       C. clock                      D. wall

2.   A. washing                       B. drop                       C. boring                    D. daughter

3.   A. chop                            B. document              C. bottle                     D. audience

4.   A. what                             B. water                      C. salt                         D. hat

5.   A. problem                      B. talk                         C. wash                      D. yoghurt

UNIT 3: Sounds /g/ &/k/

1.   A. generation                  B. goose                     C. ginger                    D. engineer

2.   A. question                      B. mosquito               C. mosque                  D. unique

3.   A. mechanic                    B. stomachache        C. Christmas              D. chance

4.   A. giggle                          B. gone                       C. engine                   D. forget

5.   A. complete                     B. compass                C. concert                  D. century

UNIT 4: Sounds /ʃ/ & /ʒ/

1.   A. chemical                     B. delicious               C. especially             D. musician

2.   A. machine                      B. chef                        C. check                     D. sugar

3.   A. generation                  B. question                C. competition          D. portion

4.   A. unusual                       B. pleasure                C. pleasant                 D. leisure

5.   A. conversation              B. discussion             C. decision                D. mission

UNIT 5: Sounds /ɒ/ & /ɔ:/

1.   A. naughty                       B. floor                       C. clock                      D. wall

2.   A. washing                       B. drop                       C. boring                    D. daughter

3.   A. chop                            B. document              C. bottle                     D. audience

4.   A. what                             B. water                      C. salt                         D. hat

5.   A. problem                      B. talk                         C. wash                      D. yoghurt

PRONUNCIATION

Choose the word which has different sound in the underlined part.

UNIT 1:  Sounds /ɜ:/ & /ə/

1.   A. prefer                                      B. dinner                                C. water                                  D. brother

2.   A. turn                              B. put                          C. burn                       D. fur

3.   A. further                         B. answer                   C. future                     D. teacher

4.   A. learner                         B. prefer                     C. sister                      D. return

5.   A. concern                       B. control                   C. correct                   D. hot

UNIT 2: Sounds/f/ & /v/

1.   A. surf                              B. roof                        C. of                            D. father

2.   A. laugh                           B. though                   C. cough                     D. enough

3.   A. of                                 B.funny                      C. wife                        D. bookshelf

4.   A. fork                              B. vampire                 C. move                      D. of

5.   A. rough                           B. fast                         C. although                D.ferry

L:

PRONUNCIATION

Choose the word which has different sound in the underlined part.

UNIT 1:  Sounds /ɜ:/ & /ə/

1.   A. prefer                                      B. dinner                                C. water                                  D. brother

2.   A. turn                              B. put                          C. burn                       D. fur

3.   A. further                         B. answer                   C. future                     D. teacher

4.   A. learner                         B. prefer                     C. sister                      D. return

5.   A. concern                       B. control                   C. correct                   D. hot

UNIT 2: Sounds/f/ & /v/

1.   A. surf                              B. roof                        C. of                            D. father

2.   A. laugh                           B. though                   C. cough                     D. enough

3.   A. of                                 B.funny                      C. wife                        D. bookshelf

4.   A. fork                              B. vampire                 C. move                      D. of

5.   A. rough                           B. fast                         C. although                D.ferry

^HT^

uy8768

uy8768

a) \(\frac{-6}{2,5}=\frac{4}{x}\)

\(\Leftrightarrow x=4.\frac{2,5}{-6}\)

\(\Leftrightarrow x=\frac{-5}{3}\)

b) \(\left|x\right|-3,5=-5\frac{1}{2}\)

\(\Leftrightarrow\left|x\right|=3,5-5\frac{1}{2}\)

\(\Leftrightarrow\left|x\right|=-2\)(vô lí)

Vậy phương trình vô nghiệm

Bài mấy để mk giải cho

Ủa sao mk ko nhìn đc câu trl của bn

mn ơi đọc câu hỏi giúp và làm hộ mình nha!