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a, x + 2/5 = 1/2
x = 1/2 + 2/5
x = 9/10 b,34/5 + x = 15/8
x = 34/5 - 15/8
x =197/40 c, x - 45/6 = 21/6 + 5/6
x - 45/6 = 26/6
x = 26/6 + 45/6
x =71/6 d,14/5 - x = 11/5 - 3/5
14/5 - x = 8/5
x = 14,5 - 8/5
x =6/5
a, x + 2/5 = 1/2
x = 1/2 + 2/5
x = 9/10
b,34/5 + x = 15/8
x = 34/5 - 15/8
x =197/40
c, x - 45/6 = 21/6 + 5/6
x - 45/6 = 26/6
x = 26/6 + 45/6
x =71/6
d,14/5 - x = 11/5 - 3/5
14/5 - x = 8/5
x = 14,5 - 8/5
x =6/5
- Làm lại.
a)\(\left(x+3\right)\times5+1=20\Leftrightarrow5x+15=19\)
\(\Leftrightarrow5x=4\Leftrightarrow x=\frac{4}{5}\)
b)sai đề
c)\(2\frac{3}{7}\times x+1\frac{5}{4}=5\frac{3}{42}\)\(\Leftrightarrow\frac{17}{7}\times x+\frac{9}{4}=\frac{71}{14}\) \(\Leftrightarrow\frac{17}{7}\times x+\frac{63}{28}=\frac{142}{28}\)
\(\Leftrightarrow\frac{17}{7}\times x=\frac{79}{28}\Leftrightarrow x=\frac{17}{7}:\frac{79}{28}\) \(\Leftrightarrow x=\frac{17}{7}\times\frac{28}{79}\Leftrightarrow x=\frac{476}{553}=\frac{68}{79}\)
d)\(10\frac{2}{3}-x:\frac{6}{7}=8\frac{1}{3}-6\frac{2}{7}\Leftrightarrow\frac{32}{3}-x:\frac{6}{7}=\frac{25}{3}-\frac{44}{7}\) \(\Leftrightarrow\frac{224}{21}-x:\frac{6}{7}=\frac{75}{21}-\frac{132}{21}\Leftrightarrow-\frac{57}{21}-\frac{224}{21}\)
\(\Leftrightarrow-x:\frac{6}{7}=-\frac{281}{21}\Leftrightarrow-x=-\frac{281}{21}\times\frac{6}{7}\) \(\Leftrightarrow-x=-\frac{1686}{147}\Leftrightarrow x=\frac{562}{49}=11\frac{23}{49}\)
a, x + \(\frac{1}{4}=\frac{5}{8}\)
x = \(\frac{5}{8}-\frac{1}{4}\)
x = \(\frac{5}{8}-\frac{2}{8}\)
x = \(\frac{3}{8}\)
b, x - \(\frac{1}{3}=\frac{1}{6}\)
x = \(\frac{1}{6}+\frac{1}{3}\)
x = \(\frac{1}{6}+\frac{2}{6}\)
x = \(\frac{3}{6}\)
x = \(\frac{1}{2}\)
c, \(Xx\frac{3}{5}=\frac{9}{10}\)
\(X=\frac{9}{10}:\frac{3}{5}\)
\(X=\frac{9}{10}x\frac{5}{3}\)
\(X=\frac{45}{30}\)
\(X=\frac{3}{2}\)
d, \(X:\frac{1}{6}=18\)
\(X=18x\frac{1}{6}\)
\(X=3\)
Bài 2
a) \(x\times1\frac{1}{4}=3\frac{3}{4}\)
\(x\times\frac{5}{4}=\frac{15}{4}\)
\(x=\frac{15}{4}.\frac{4}{5}\)
\(x=3\)
b) \(x-\frac{3}{4}=6\times\frac{3}{8}\)
\(x-\frac{3}{4}=\frac{9}{4}\)
\(x=\frac{9}{4}+\frac{3}{4}\)
\(x=3\)
Những câu còn lại tương tự
`A = 1 . 2 + 2 . 3 + 3 . 4 + ... + 50 . 51`
`3A = 1 . 2 . 3 + 2 . 3 . (4 - 1) + 3 . 4 . (5 - 2) + ... + 50 . 51 . (52 - 49)`
`3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + ... + 50 . 51 . 52 - 49.50.51`
`3A = 50 . 51 . 52`
`A = 44200`
`B = 2 . 4 + 4.6 + ... + 18.20`
`6B = 2.4.6 + 4.6.(8-2) + ... + 18.20.(22-16)`
`6B = 2.4.6 + 4.6.8 - 2.4.6 + ... + 18.20.22 - 16 . 18. 20`
`6B = 18 . 20 . 22`
`B = 1320`