Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a, \(\frac{1}{2}x\frac{2}{7}+\frac{3}{7}:2+\frac{1}{2}:\frac{7}{2}\)
= \(\frac{1}{2}x\frac{2}{7}+\frac{3}{7}x\frac{1}{2}+\frac{1}{2}x\frac{2}{7}\)
= \(\frac{1}{2}x\left(\frac{2}{7}+\frac{3}{7}+\frac{2}{7}\right)\)
= \(\frac{1}{2}x1\)
= \(\frac{1}{2}\)
\(a,\frac{1}{2}x\frac{2}{7}+\frac{3}{7}:2+\frac{1}{2}:\frac{7}{2}\)
\(=\frac{1}{2}x\frac{2}{7}+\frac{3}{7}x\frac{1}{2}+\frac{1}{2}x\frac{2}{7}\)
\(=\frac{1}{2}x\left(\frac{2}{7}+\frac{3}{7}+\frac{2}{7}\right)\)
\(=\frac{1}{2}x1\)
\(=\frac{1}{2}\)
\(b,\frac{3}{7}x\frac{3}{5}+\frac{3}{5}:7+\frac{3}{7}:\frac{5}{3}\)
\(=\frac{3}{7}x\frac{3}{5}+\frac{3}{5}x\frac{1}{7}+\frac{3}{7}x\frac{3}{5}\)
\(=\frac{3}{5}x\left(\frac{3}{7}+\frac{1}{7}+\frac{3}{7}\right)\)
\(=\frac{3}{5}x1\)
\(=\frac{3}{5}\)
a, (3/10+4/5 ><1/2):(17/9-4/3:3)
= (3/10+4/10):(17/9-4/9)
=7/10:13/9
=7/10><9/13
=63/130
(>< là dấu nhân)
a) \(\frac{3}{3.5}+\frac{3}{5.7}+\frac{3}{7.9}+...+\frac{3}{97.99}\)
\(=\frac{3}{2}.\left(\frac{1}{3}-\frac{1}{5}\right)+\frac{3}{2}.\left(\frac{1}{5}-\frac{1}{7}\right)+\frac{3}{2}.\left(\frac{1}{7}-\frac{1}{9}\right)+...+\frac{3}{2}.\left(\frac{1}{97}-\frac{1}{99}\right)\)
\(=\frac{3}{2}.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{97}-\frac{1}{99}\right)\)
\(=\frac{3}{2}.\left(\frac{1}{3}-\frac{1}{99}\right)\)
\(=\frac{3}{2}.\frac{32}{99}\)
\(=\frac{16}{33}\)
b)
\(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{100.103}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{100}-\frac{1}{103}\)
\(=1-\frac{1}{103}\)
\(=\frac{102}{103}\)
\(\left(\frac{2}{3}+\frac{1}{3}:\frac{3}{4}+\frac{5}{9}\right).y-3=25\%+\frac{7}{4}\)
\(\Rightarrow\left(\frac{2}{3}+\frac{4}{9}+\frac{5}{9}\right).y-3=\frac{1}{4}+\frac{7}{4}\)
\(\Rightarrow\left(\frac{2}{3}+1\right).y-3=2\)
\(\Rightarrow\frac{5}{3}.y-3=2\)
\(\Rightarrow y-3=2:\frac{5}{3}\)
\(\Rightarrow y-3=\frac{6}{5}\)
\(\Rightarrow y=\frac{6}{5}+3\)
\(\Rightarrow y=\frac{21}{5}\)
bằng 1/2 nha