Các câu hỏi tương tự
Cho A = \(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\)
B = \(\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{10}\right)-2\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{10}\right)\)
a) So sánh A và B
b) Chứng minh A = \(\frac{1}{6}+\frac{1}{7}+\frac{1}{8}+\frac{1}{9}+\frac{1}{10}\)
Thực hiện phép tính
a) \(\left(4\frac{1}{9}+3\frac{1}{4}\right).2\frac{1}{4}+2\frac{3}{4}\)
b) \(1+\left(\frac{9}{10}-\frac{4}{5}\right):3\frac{1}{6}\)
c) (-7 + |13|) - (13 - |-7| - 25) - (25 + |-10| - 9 )
So Sánh :
a) \(\frac{9^{10}-4}{9^{10}-5}\) và \(\frac{9^{10}-2}{9^{10}-3}\)
b)\(\frac{2.7^{10}-1}{7^{10}}\) và \(\frac{2.7^{10}+1}{7^{10}+1}\)
\(A=\left\{\frac{1999}{2011}-\frac{2011}{1999}\right\}-\left\{\frac{-12}{1999}-\frac{12}{2011}\right\}\)
\(B=\frac{2}{5}+\left(\frac{3}{11}+\frac{-2}{5}\right)\)
\(C=\frac{-5}{7}.\frac{4}{13}+\frac{-5}{7}.\frac{9}{13}+\frac{-2}{7}\)
\(D=\frac{-9}{10}.\frac{5}{14}+\frac{1}{10}.\left(\frac{-9}{2}\right)+\frac{1}{7}.\left(\frac{-9}{10}\right)\)
Bài 2: Thực hiện phép tính:
a)\((4\frac{1}{9}+3\frac{1}{4}).2\frac{1}{4}+2\frac{3}{4}\)
b) \(1+(\frac{9}{10}-\frac{4}{5})\div3\frac{1}{6}\)
c) \((-7+|13|)-\left(13-|-7|-25\right)-\left(25-|-10|-9\right)\)
So sánh:
a) \(\frac{n}{3.n+1}\)và \(\frac{2.n}{6.n+1}\)
b) A= \(\frac{10^7+1}{10^8+1}\)và B= \(\frac{10^8+1}{10^9+1}\)
mau nha các bạn cần gấp 
1.Tính nhanh :a)Mfrac{17}{5}.frac{-31}{125}.frac{1}{2}.frac{10}{17}.frac{-1}{2^3}b)Nfrac{1}{7}.frac{5}{9}+frac{5}{9}.frac{2}{7}+frac{5}{9}.frac{1}{7}+frac{5}{9}.frac{3}{7}c)Pfrac{6}{7}.frac{8}{13}+frac{6}{9}.frac{9}{7}-frac{3}{13}.frac{6}{7}d)Qleft(frac{-9}{25}right)frac{53}{3}-left(frac{-5}{3}right)^2.frac{22}{3}2. Tính :a)Pleft(1-frac{1}{2}right).left(1-frac{1}{3}right).left(1-frac{1}{4}right)....left(1-frac{1}{1000}right)b)Qfrac{7}{3.5}+frac{7}{5.7}+frac{7}{7.9}+...+frac{7}{37.39}
Đọc tiếp
1.Tính nhanh :
a)M=\(\frac{17}{5}.\frac{-31}{125}.\frac{1}{2}.\frac{10}{17}.\frac{-1}{2^3}\)
b)N=\(\frac{1}{7}.\frac{5}{9}+\frac{5}{9}.\frac{2}{7}+\frac{5}{9}.\frac{1}{7}+\frac{5}{9}.\frac{3}{7}\)
c)P=\(\frac{6}{7}.\frac{8}{13}+\frac{6}{9}.\frac{9}{7}-\frac{3}{13}.\frac{6}{7}\)
d)Q=\(\left(\frac{-9}{25}\right)\frac{53}{3}-\left(\frac{-5}{3}\right)^2.\frac{22}{3}\)
2. Tính :
a)P=\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{1000}\right)\)
b)Q=\(\frac{7}{3.5}+\frac{7}{5.7}+\frac{7}{7.9}+...+\frac{7}{37.39}\)
Tính nhanh:
M=\(\frac{-7}{9}.\frac{15}{49}.\frac{9}{7}.15.\frac{14}{15}\)
N=\(\frac{5}{9}.\frac{4}{7}.\frac{10}{3}+\frac{15}{45}.\frac{3}{7}.\frac{1}{2}\)
a) Tìm số tự nhiên n để \(\frac{7}{n+9};\frac{8}{n+10};\frac{9}{n+11};\frac{10}{n+12};\frac{11}{n+13}\)tối giản
b) A = \(\frac{n-1}{n+4}\)tìm n thuộc Z để A tối giản