Question

Answer 1

Câu 1:

\(-\dfrac{5}{7}-\dfrac{1}{3}+\dfrac{19}{7}=-\dfrac{15}{21}-\dfrac{7}{21}+\dfrac{57}{21}=\dfrac{35}{21}=\dfrac{5}{3}\)

c.

\(\dfrac{16}{48}-\dfrac{45}{30}+1=\dfrac{80}{240}-\dfrac{360}{240}+\dfrac{240}{240}=\dfrac{40}{240}=-\dfrac{1}{6}\)

 

Answer 2

Câu 4: 

a) Để A là phân số thì \(n-3\ne0\)

hay \(n\ne3\)