\(\frac{10}{18}\)+\(\frac{4}{9}\)+\(\frac{26}{10}\)+\(\frac{12}{5}\)+\(\frac{9}{15}\)
\(\frac{10}{18}\)+\(\frac{4}{9}\)+\(\frac{1}{8}\)+\(\frac{1}{16}\)+\(\frac{1}{32}\)+....+\(\frac{1}{64}\)+\(\frac{1}{128}\)
\(\frac{2}{6}\)+\(\frac{2}{12}\)+\(\frac{2}{20}\)+.....+\(\frac{2}{90}\)+\(\frac{2}{100}\)
bài này tính nhanh nha
\(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}\)
\(=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\)
\(=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\right)\)
\(=1+\frac{28}{5}\)
\(=\frac{33}{5}\)
Ta có:
a) \(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{9}{15}=1+1+\frac{9}{15}=1\frac{9}{15}\)
b)\(\frac{10}{18}+\frac{4}{9}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{16}{128}+\frac{8}{128}+\frac{4}{128}+\frac{2}{128}+\frac{1}{128}\right)\)
\(=1+\frac{31}{128}=1\frac{31}{128}\)
c) Sửa đề : \(\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+...+\frac{2}{90}+\frac{2}{110}\)
\(=2.\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}+\frac{1}{10.11}\right)\)
\(=2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{11}\right)\)
\(=2.\left(\frac{1}{2}-\frac{1}{11}\right)=2.\frac{9}{22}=\frac{9}{11}\)
Mình nghĩ đề vậy đúng hơn. Nếu sai bạn nhắn tin cho mình nhé!
câu cuối cùng mình chép nhầm đề bài con số cuối cùng là\(\frac{2}{110}\)
