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f) \(\dfrac{-x}{3}=2\dfrac{1}{7}\div\dfrac{5}{7}\)
\(\dfrac{-x}{3}=\dfrac{15}{7}\div\dfrac{5}{7}\)
\(\dfrac{-x}{3}=3\)
\(-x=3\cdot3\)
\(-x=9\)
\(x=-9\)
g) \(\dfrac{5}{4}+\dfrac{1}{4}\div x=1\dfrac{3}{8}\)
\(\dfrac{5}{4}+\dfrac{1}{4}\div x=\dfrac{11}{8}\)
\(\dfrac{1}{4}\div x=\dfrac{11}{8}-\dfrac{5}{4}\)
\(\dfrac{1}{4}\div x=\dfrac{1}{8}\)
\(x=\dfrac{1}{4}\div\dfrac{1}{8}\)
\(x=2\)
TK :
5x + 5x +2 = 650
5x + 5x . 52 = 650
5x .( 1 +25 ) = 650
5x .26 = 650
5x = 650 / 26 =25
5x = 52
nên x=2
\(\dfrac{-7}{x+1}=\dfrac{6}{x+27}\)
\(\Rightarrow-7x-189=6x+6\)
\(\Rightarrow-7x-6x=6+189\)
\(\Rightarrow-13x=195\)
\(\Rightarrow x=-15\)
Vay x = -15
`2/3 . 6/9+25/54:5/6`
`=2/3 . 2/3+25/54 . 6/5`
`=4/9+5/9=9/9=1`
\(\dfrac{2}{3}\cdot\dfrac{6}{9}+\dfrac{25}{54}:\dfrac{5}{6}=\dfrac{4}{9}+\dfrac{5}{9}=\dfrac{9}{9}=1\)