3/2 . x + ( 5/3 - 3/2) : 2/3 = 5/3
3/2.x + 1/6 : 2/3 = 5/3
3/2.x + 1/4 = 5/3
3/2.x = 5/3 - 1/4
3/2.x=17/12
x= 17/12 : 3/2
x= 17/18
Vậy...
Bài 2:
4/5x7 + 4/7x9 + 4/9x11 +...+4/17x19
= 2(2/5.7 + 2/7.9 + 2/9.11+...+ 2/17/19)
= 2( 1/5 - 1/7 + 1/7 -1/9 + 1/9 -1/11 +...+ 1/17 - 1/19)
= 2( 1/5- 1/19)
= 2 . 14/95
= 28/95
Trả lời:
Bài 1
\(\frac{3}{2}\times x+\left(\frac{5}{3}-\frac{3}{2}\right)\div\frac{2}{3}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x+\frac{1}{6}\div\frac{2}{3}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x+\frac{1}{6}\times\frac{3}{2}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x+\frac{1}{4}=\frac{5}{3}\)
\(\Leftrightarrow\frac{1}{6}\times x=\frac{17}{12}\)
\(\Leftrightarrow x=\frac{17}{2}\)
Vậy \(x=\frac{17}{2}\)
Trả lời
Bài 1
\(\frac{3}{2}\times x+\left(\frac{5}{3}-\frac{3}{2}\right)\div\frac{2}{3}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x+\frac{1}{6}\div\frac{2}{3}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x+\frac{1}{6}\times\frac{3}{2}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x+\frac{1}{4}=\frac{5}{3}\)
\(\Leftrightarrow\frac{3}{2}\times x=\frac{17}{12}\)
\(\Leftrightarrow x=\frac{17}{18}\)
Vậy \(x=\frac{17}{18}\)
Bài 2
\(\frac{4}{5\times7}+\frac{4}{7\times9}+\frac{4}{9\times11}+...+\frac{4}{17\times19}\)
\(=2\times\left(\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}+...+\frac{2}{17\times19}\right)\)
\(=2\times\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+...+\frac{1}{17}-\frac{1}{19}\right)\)
\(=2\times\left(\frac{1}{5}-\frac{1}{19}\right)\)
\(=2\times\frac{14}{95}\)
\(=\frac{28}{95}\)
