tìm x biết
a) |3/2 -1/3 | *-6/7x-7/5=25/7*21/5
b) ( 4/3 – 25%x – 5/12)-3x= 1,6 : 3/5
c) (-2/3)^2 : (x-1)+ 3 ^1001* [7/4 – 3/2^2 +1]= 2/9
d) 1/2 (4x-6) -1= 2 [ 1/2x+3 ]
tìm x biết a) |3/2 -1/3 | *-6/7x-7/5=25/7*21/5 b) ( 4/3 – 25%x – 5/12)-3x= 1,6 : 3/5 c) (-2/3)^2 : (x-1)+ 3 ^1001* [7/4 – 3/2^2 +1]= 2/9 d) 1/2 (4x-6)
By Isabelle
Đáp án:
$\begin{array}{l}
a)\left| {\dfrac{3}{2} – \dfrac{1}{3}} \right|.\dfrac{{ – 6}}{7}x – \dfrac{7}{5} = \dfrac{{25}}{7}.\dfrac{{21}}{5}\\
\Rightarrow \left| {\dfrac{{9 – 2}}{6}} \right|.\dfrac{{ – 6}}{7}x – \dfrac{7}{5} = 5.3\\
\Rightarrow \dfrac{7}{6}.\dfrac{{ – 6}}{7}x = 15 + \dfrac{7}{5}\\
\Rightarrow – x = \dfrac{{75 + 7}}{5}\\
\Rightarrow x = \dfrac{{ – 82}}{5}\\
b)\left( {\dfrac{4}{3} – 25\% x – \dfrac{5}{{12}}} \right) – 3x = 1,6:\dfrac{3}{5}\\
\Rightarrow \left( {\dfrac{4}{3} – \dfrac{1}{4}x – \dfrac{5}{{12}}} \right) – 3x = \dfrac{8}{5}.\dfrac{5}{3}\\
\Rightarrow \dfrac{4}{3} – \dfrac{5}{{12}} – \dfrac{1}{4}x – 3x = \dfrac{8}{3}\\
\Rightarrow \left( { – \dfrac{1}{4} – 3} \right).x = \dfrac{8}{3} + \dfrac{5}{{12}} – \dfrac{4}{3}\\
\Rightarrow \dfrac{{ – 13}}{4}.x = \dfrac{5}{{12}} + \dfrac{4}{3} = \dfrac{{21}}{{12}} = \dfrac{7}{4}\\
\Rightarrow x = \dfrac{7}{4}.\dfrac{{ – 4}}{{13}} = \dfrac{{ – 7}}{{13}}\\
c){\left( { – \dfrac{2}{3}} \right)^2}:\left( {x – 1} \right) + {3^{1001}}.\left( {\dfrac{7}{4} – \left( {\dfrac{3}{{{2^2}}} + 1} \right)} \right) = \dfrac{2}{9}\\
\Rightarrow \dfrac{4}{9}:\left( {x – 1} \right) + {3^{1001}}.\left( {\dfrac{7}{4} – \dfrac{3}{4} – 1} \right) = \dfrac{2}{9}\\
\Rightarrow \dfrac{4}{9}:\left( {x – 1} \right) + {3^{1001}}.0 = \dfrac{2}{9}\\
\Rightarrow \dfrac{4}{9}:\left( {x – 1} \right) = \dfrac{2}{9}\\
\Rightarrow x – 1 = \dfrac{4}{9}:\dfrac{2}{9} = 2\\
\Rightarrow x = 2 + 1 = 3\\
d)\dfrac{1}{2}\left( {4x – 6} \right) – 1 = 2.\left( {\dfrac{1}{2}x + 3} \right)\\
\Rightarrow \dfrac{1}{2}.2.\left( {2x – 3} \right) – 1 = 2.\dfrac{1}{2}.x + 2.3\\
\Rightarrow 2x – 3 – 1 = x + 6\\
\Rightarrow 2x – x = 6 + 3 + 1\\
\Rightarrow x = 10
\end{array}$