25% - \(1\dfrac{1}{2}\) -( \(-\dfrac{1^2}{2}\)) + 0,25 : \(\dfrac{1}{12}\)

\(\dfrac{-20}{23}\)+\(\dfrac{2}{3}\)-\(\dfrac{3}{23}\)+\(\dfrac{2}{5}\)+\(\dfrac{7}{15}\)

\(\dfrac{1}{2}\)+\(\dfrac{13}{19}\)-\(\dfrac{4}{9}\)+\(\dfrac{6}{19}\)+\(\dfrac{5}{18}\)

So sánh hai ps A=\(\dfrac{10^8+1}{10^9+1}\) và B=\(\dfrac{10^9+1}{10^{10}+1}\)

Bài 3: Chứng minh các phân số sau tối giản

a, A=\(\dfrac{n+1}{n+2}\)       b, B=\(\dfrac{n+1}{3n+4}\)         c, C=\(\dfrac{3n+2}{5n+3}\)          d, D=\(\dfrac{12n+1}{30n+2}\)

Cho A= \(\dfrac{1}{1.5}\)+\(\dfrac{3}{5.11}\)\(\dfrac{4}{11.19}\)+\(\dfrac{5}{19.29}\)+\(\dfrac{6}{29.41}\); B=\(\dfrac{1}{1.4}\)+\(\dfrac{2}{4.10}\)+\(\dfrac{3}{10.19}\)+\(\dfrac{4}{19.31}\) Chứng tỏ rằng A>B

Chứng minh:

S\(_2\)= \(\dfrac{1}{2^2}\)+\(\dfrac{1}{3^2}\)+\(\dfrac{1}{4^1}\)+...+\(\dfrac{1}{50^2}\)<1

Chứng minh:

S\(_1\)=\(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+\(\dfrac{1}{3.4}\)+...+\(\dfrac{1}{99.100}\)<1

Tính giá trị biểu thức sau: 

P=\(\dfrac{1}{1+2}\)+\(\dfrac{1}{1+2+3}\)+\(\dfrac{1}{1+2+3+4}\)+...+\(\dfrac{1}{1+2+3+4+...+2021}\)

C= \(\dfrac{x+3}{x+1}\)

Tìm C 

D=\(\dfrac{2x+10}{x+3}\)

Tìm D