Ta có: f(1)=g(2)

\(\Rightarrow\)\(2.1^2+a.1+4=2^2-5.2-b\)

\(\Rightarrow6+a=-6-b\)

\(\Rightarrow a+12=-b\) (*)

Ta có: f(-1) = g(5)

\(\Rightarrow2.\left(-1\right)^2+a.\left(-1\right)+4=5^2-5.5-b\)

\(\Rightarrow2-a+4=-b\)

\(\Rightarrow6-a=-b\) (**)

Từ (*) và (**), ta có:

\(a+12=6-a\)

\(\Rightarrow2a=-6\)

\(\Rightarrow a=-3\)

Thay a=-3 vào biểu thức 6-a=-b, ta có:

6-(-3)=-b

\(\Rightarrow9=-b\)

\(\Rightarrow b=-9\)

\(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{12}\)

\(\Rightarrow x\left(\dfrac{2}{3}-\dfrac{1}{2}\right)=\dfrac{5}{12}\)

\(\Rightarrow x.\dfrac{1}{6}=\dfrac{5}{12}\)

\(\Rightarrow x=\dfrac{5}{2}\)

\(A=\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}+\dfrac{1}{8.9}+\dfrac{1}{9.10}+\dfrac{1}{10.11}+\dfrac{1}{11.12}\)

\(A=\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{12}\)

\(A=\dfrac{1}{5}-\dfrac{1}{12}\)

\(A=\dfrac{7}{60}\)

Mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that is CLOSEST in meaning to the underlined part in each of the following questions.

School uniform is compulsory in most of Vietnamese schools.

A. divided

B. paid

C. required

D. depended

Ta có:

\(50\%x+\dfrac{2}{3}x=x+4\)

\(\Rightarrow\dfrac{1}{2}x+\dfrac{2}{3}x=x+4\)

\(\Rightarrow x\left(\dfrac{1}{2}+\dfrac{2}{3}\right)=x+4\)

\(\Rightarrow\dfrac{7}{6}x=x+4\)

\(\Rightarrow7x=6.\left(x+4\right)\)

\(\Rightarrow7x=6x+4\)

\(\Rightarrow x=4\)