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a) x=\(\dfrac{5.6}{-10}=-3.\)
b) y=\(\dfrac{3.77}{-33}=-7.\)
a) x.21=6.7
x.21=42
x=42:21
x = 2
b) y . 20 = -5.28
y.20 = -140
y = (-140) : 20
y = -7
a)=>x*21=7*6
=>x*21=42
=>x=42/21
x=2
b)=>y*20=(-5)*28
=>y*20=-140
=>y=-140/20
y=-7
9) \(\dfrac{x}{4}=\dfrac{9}{x}\)
Theo định nghĩa về hai phân số bằng nhau, ta có:
\(4\cdot9=x^2\\ 36=x^2\Rightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)
8)
\(x:\dfrac{5}{3}+\dfrac{1}{3}=-\dfrac{2}{5}\\ x:\dfrac{5}{3}=-\dfrac{2}{5}+\dfrac{1}{3}\\ x:\dfrac{5}{3}=-\dfrac{1}{15}\\ x=\dfrac{1}{15}\cdot\dfrac{5}{3}\\ x=\dfrac{1}{9}\)
7)
\(2x-16=40+x\\ 2x-x=40+16\\ x\left(2-1\right)=56\\ x=56\)
6)
\(1\dfrac{1}{2}+x=\dfrac{3}{2}-7\\ \dfrac{3}{2}+x=\dfrac{3}{2}-7\\ \dfrac{3}{2}-\dfrac{3}{2}=-7-x\\ -7-x=0\\ x=-7-0\\ x=-7\)
5)
\(3\dfrac{1}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\\ \dfrac{7}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\\ \dfrac{1}{2}x=\dfrac{7}{2}-\dfrac{2}{3}\\ \dfrac{1}{2}x=\dfrac{17}{6}\\ x=\dfrac{17}{6}:\dfrac{1}{2}\\ x=\dfrac{17}{3}\)
4)
\(x\cdot\left(x+1\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)
3)
\(\left(\dfrac{2x}{5}+2\right):\left(-4\right)=-1\dfrac{1}{2}\\ \left(\dfrac{2x}{5}+2\right):\left(-4\right)=-\dfrac{3}{2}\\ \dfrac{2x}{5}+2=-\dfrac{3}{2}\cdot\left(-4\right)\\ \dfrac{2x}{5}+2=6\\ \dfrac{2x}{5}=6-2\\ \dfrac{2x}{5}=4\\ 2x=4\cdot5\\ 2x=20\\ x=20:2\\ x=10\)
2)
\(\dfrac{1}{3}+\dfrac{1}{2}:x=-0,25\\ \dfrac{1}{3}+\dfrac{1}{2}:x=-\dfrac{1}{4}\\ \dfrac{1}{2}:x=-\dfrac{1}{4}-\dfrac{1}{3}\\ \dfrac{1}{2}:x=-\dfrac{7}{12}\\ x=\dfrac{1}{2}:-\dfrac{7}{12}\\ x=-\dfrac{6}{7}\)
1)
\(\dfrac{4}{3}+x=\dfrac{2}{15}\\ x=\dfrac{2}{15}-\dfrac{4}{3}x=-\dfrac{6}{5}\)
các bạn ơi giúp mìh với mìh đag cần gấp ai nhanh và đúng thì mih tick cho
a) \(\left(3\dfrac{1}{3}-x\right)1\dfrac{1}{6}=\dfrac{7}{24}\)
\(\Leftrightarrow\left(\dfrac{10}{3}-x\right)\dfrac{7}{6}=\dfrac{7}{24}\)
\(\Leftrightarrow\dfrac{10}{3}-x=\dfrac{7}{24}:\dfrac{7}{6}\)
\(\Leftrightarrow\dfrac{10}{3}-x=\dfrac{1}{4}\)
\(\Leftrightarrow x=\dfrac{10}{3}-\dfrac{1}{4}\)
\(\Leftrightarrow x=\dfrac{37}{12}\).
b) \(\left(4,5-2x\right):\dfrac{3}{4}=1\dfrac{1}{3}\)
\(\Leftrightarrow\left(4,5-2x\right):\dfrac{3}{4}=\dfrac{4}{3}\)
\(\Leftrightarrow4,5-2x=\dfrac{4}{3}.\dfrac{3}{4}\)
\(\Leftrightarrow4,5-2x=1\)
\(\Leftrightarrow2x=4,5-1\)
\(\Leftrightarrow2x=3,5\)
\(\Leftrightarrow x=\dfrac{35}{2}\).
6. \(\dfrac{x}{4}=\dfrac{9}{x}\)
=>x2=4.9=36
=>x\(\in\)\(\left\{-6;6\right\}\)
\((\dfrac{2x}{5}+2):\left(-4\right)=-1\dfrac{1}{2}\)
(\(\dfrac{2x}{5}+2):\left(-4\right)=-\dfrac{3}{2}\)
\(\dfrac{2x}{5}=-\dfrac{3}{2}.\left(-4\right)\)
\(\dfrac{2x}{5}=6\)
\(\dfrac{2x}{5}=\dfrac{30}{5}\)
2x = 30
x = 30 : 2 = 15
b) \(\left(\dfrac{1}{2}+2x\right).\dfrac{2}{3}=\dfrac{5}{6}\\ \dfrac{1}{2}+2x=\dfrac{5}{6}:\dfrac{2}{3}\\ \dfrac{1}{2}+2x=\dfrac{5}{6}.\dfrac{3}{2}\\ \dfrac{1}{2}+2x=\dfrac{5}{4}\\ 2x=\dfrac{5}{4}-\dfrac{1}{2}\\ 2x=\dfrac{5}{4}-\dfrac{2}{4}\\ 2x=\dfrac{3}{4}\\ x=\dfrac{3}{4}:2\\ x=\dfrac{1}{2}\)
Cho mình sửa lại nha:
\(\left(\dfrac{1}{2}+2x\right).\dfrac{2}{3}=\dfrac{5}{6}\\ \dfrac{1}{2}+2x=\dfrac{5}{6}:\dfrac{2}{3}\\ \dfrac{1}{2}+2x=\dfrac{5}{6}.\dfrac{3}{2}\\ \dfrac{1}{2}+2x=\dfrac{5}{4}\\ 2x=\dfrac{5}{4}-\dfrac{1}{2}\\ 2x=\dfrac{5}{4}-\dfrac{2}{4}\\ 2x=\dfrac{3}{4}\\ x=\dfrac{3}{4}:2\\ x=\dfrac{3}{8}\)
=>2x=-18
hay x=-9