Trả lời:
\(\frac{2}{35}+\frac{4}{77}+\frac{2}{143}+\frac{4}{221}+\frac{6}{391}+\frac{2}{575}+\frac{2}{675}\)
\(=\frac{2}{5.7}+\frac{5}{7.11}+\frac{2}{11.13}+\frac{4}{13.17}+\frac{6}{17.23}+\frac{2}{23.25}+\frac{2}{25.27}\)
\(=\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{23}+\frac{1}{23}-\frac{1}{25}+\frac{1}{25}-\frac{1}{27}\)
\(=\frac{1}{5}-\frac{1}{27}\)
\(=\frac{22}{135}\)
Tính giá trị biểu thức sau một cách hợp lý:
\(\dfrac{2}{35}\) + \(\dfrac{4}{77}\) + \(\dfrac{2}{143}\) + \(\dfrac{4}{221}\) + \(\dfrac{2}{323}\) + \(\dfrac{4}{437}\) +\(\dfrac{2}{575}\)
Tính nhanh 2/35 + 4/77 + 2/143 + 4/221 + 2/323 + 4/437 + 2/575
TÍNH NHANH :
2/35 + 4/77 + 2/143 + 4/221 + 2/333 + 4/437 + 2/575
B=2/35+4/77+2/143+4/221+2/323+4/137+2/575
C=8:4/5-7 1/5x5/4
\(A=\frac{2}{35}+\frac{4}{77}+\frac{2}{143}+\frac{4}{221}+\frac{2}{323}+\frac{4}{437}+\frac{2}{575}\)
\(\frac{2}{35}+\frac{4}{77}+\frac{2}{143}+\frac{4}{221}+\frac{2}{323}+\frac{4}{437}+\frac{2}{575}\)
\(Tínhnhanh\frac{2}{35}+\frac{4}{77}+\frac{2}{143}+\frac{4}{221}+\frac{2}{323}+\frac{4}{437}+\frac{2}{575}\)
Tính giá trị biểu thức sau một cách hợp lí:
\(\frac{2}{35}\)+\(\frac{4}{77}\)+\(\frac{2}{143}\)+\(\frac{4}{221}\)+\(\frac{2}{323}\)+\(\frac{4}{437}\)+\(\frac{2}{575}\)
tìm x
\(\frac{1999x2011-1999}{2010x1998-2010}\)
\(\frac{2}{35}+\frac{4}{77}+\frac{2}{143}+\frac{4}{221}+\frac{2}{323}+\frac{4}{437}+\frac{2}{575}\)
mọi người cho em hỏi bài đầu tiên có sai đề hông ạ