Mark the letter A, B, C or D to indicate the word whose underlined part differs from the others.

A. camel             B. buffalo                  C. cattle                D. paddy

Mark the letter A, B, C or D to indicate the word CLOSEST in meaning to the underlined word in each of the following questions.

Some fields are planted with crops for several years, and then returned to grasslands for the cattle.

A. field             B. paddy field                       C. shed            D. passtures

 Mark the letter A, B, C or D to indicate the word OPPOSITE in meaning to the underlined word in each of the following questions.

Doing morning exercises is an (a) exciting activity for students.

A. boring                   B. happy                    C. hard           D. interesting

Mark the letter A, B, C or D to indicate the correct answer to each of the following questions.

She is _______________ student in my class.

A. most hard-working                          B. more hard-working 

C. the most hard-working                      D. as hard-working

Mark the letter A, B, C or D to indicate the word whose underlined part differs from the others.

A. hooked            B. picked                   C. gathered          D. kissed

Mark the letter A, B, C or D to indicate the word OPPOSITE in meaning to the underlined word in each of the following questions.

Ethnic minority people in the mountains are still using basic tools to do their farm work.

A. complicated         B. simple            C. new                  D. developed

33/ more beautifully

34/hate making

35/ more expensive

36/ used to cycle

Đề bài cho Fe có hóa trị III rồi sao phải tìm nữa chi???

Áp dụng dãy tỉ số bằng nhau ta có:

\(\dfrac{a}{3}=\dfrac{b}{4}=\dfrac{a+b}{3+4}=\dfrac{21}{7}=3\)

\(\Rightarrow\left\{{}\begin{matrix}a=3.3=9\\b=3.4=12\end{matrix}\right.\)

= (x - 3). (x² + x.3 + 3²) = (x - 3).(x² + 3x +9)

đọc kĩ đi. Mik làm hết mà =.=

2² . 2² - 2² : 2² = 2⁴ - 1 = 16 - 1= 15

Bài 1:

5x.(xy - 3y + x)= 5x²y - 15xy + 5x²

Bài 2:

(x + 3).(x² + 3x - 5) = x.(x² + 3x - 5) + 3.(x² + 3x -5)

                                = x³ + 3x² - 5x + 3x² + 9x -15

                                = x³ + 6x² +4x - 15

Bài 3: (5x - 2)² =(5x)² - 2.5x.2 + 2² = 25x² - 20x + 4

Bài 4:

a, = 3x.(x - 2y) - 6y.(x - 2y) = (x - 2y).(3x - 6y)

b, = 3x.(x + 2y) + 6.(x + 2y) = (x + 2y).(3x + 6)

a, ⇒ \(x=\dfrac{1}{6}-\dfrac{2}{5}\)

   \(\Rightarrow x=\dfrac{5}{30}-\dfrac{12}{30}\)

   \(\Rightarrow x=-\dfrac{7}{30}\)

b, \(\Rightarrow\dfrac{5}{3}x=\dfrac{1}{3}-\dfrac{2}{7}\)

    ⇒ \(\dfrac{5}{3}x=\dfrac{7}{21}-\dfrac{6}{21}\)

    \(\Rightarrow\dfrac{5}{3}x=\dfrac{1}{21}\)

    \(\Rightarrow x=\dfrac{1}{21}:\dfrac{5}{3}\)

    \(\Rightarrow x=\dfrac{1}{21}.\dfrac{3}{5}=\dfrac{1}{35}\)

c, \(\Rightarrow\left|x-\dfrac{2}{5}\right|=3+\dfrac{1}{4}\)

    \(\Rightarrow\left|x-\dfrac{2}{5}\right|=\dfrac{13}{4}\)

    \(\Rightarrow\left[{}\begin{matrix}x-\dfrac{2}{5}=\dfrac{13}{4}\\x-\dfrac{2}{5}=-\dfrac{13}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{73}{20}\\x=-\dfrac{57}{20}\end{matrix}\right.\)

d, ⇒ x.x = 2.8

    ⇒ x²   = 16

    ⇒ x²   = (\(\pm4\))²

    ⇒ x     = \(\pm4\)