38. They have worked in that company for 10 years

39. Lan can't pass the exam unless she study hard

38. They have worked in that company for 10 years

39. Lan can't pass the exam because she doesn't study hard

ko thấy gì bn ơi

\(A=\left(4x^7y^5-4x^7y^5\right)+2xy^2-4y^2+2019\)

\(=2xy^2-4y^2+2019\)

\(=2\cdot2\cdot9-4\cdot9+2019=2019\)

Sau lần 2 còn (5+5):1/2=20(kg)

Sau lần 1 còn (20+4):2/3=24*3/2=36(kg)

Trước khi bán có:

(36+3):3/4=39*4/3=52(kg)

a)

 \(0,3-\dfrac{8}{3}:\dfrac{4}{3}\cdot\dfrac{1}{5}+1\\ =\dfrac{3}{10}-\dfrac{8}{3}\cdot\dfrac{3}{4}\cdot\dfrac{1}{5}+1\\ =\dfrac{3}{10}-2\cdot\dfrac{1}{5}+1\\ =\dfrac{3}{10}-\dfrac{2}{5}+1\\ =\dfrac{9}{10}\)

b) 

\(\left(-\dfrac{1}{2}\right)^2-\dfrac{5}{8}:\left(0,5\right)^3-\dfrac{5}{3}\cdot\left(-6\right)\\ =\dfrac{1}{4}-\dfrac{5}{8}:\dfrac{1}{8}+\dfrac{5}{3}\cdot6\\ =\dfrac{1}{4}-\dfrac{5}{8}\cdot8+10\\ =\dfrac{1}{4}-5+10\\ =\dfrac{21}{4}\)

c) 

\(2+4:\left(\dfrac{2}{3}-\dfrac{1}{6}\right)\cdot\left(-2,25\right)\\ =2+4:\dfrac{1}{2}\cdot\left(-2,25\right)\\ =2+8\cdot\left(-2,25\right)\\ =2-18\\ =-16\)

d) 

\(\left(2\dfrac{5}{6}+1\dfrac{4}{9}\right):\left(10\dfrac{1}{12}-9\dfrac{1}{2}\right)\\ =\left(2+\dfrac{5}{6}+1+\dfrac{4}{9}\right):\left(10+\dfrac{1}{12}-9-\dfrac{1}{2}\right)\\ =\left(3+\dfrac{23}{18}\right):\left(1-\dfrac{5}{12}\right)\\ =\dfrac{77}{18}:\dfrac{7}{12}\\ =\dfrac{22}{3}\)

1 A

2 C

C

C.swimming