x-3/4=1/2 giúp mình với tìm x biết
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\(\dfrac{-2}{3}\left(x-\dfrac{1}{4}\right)=\dfrac{1}{3}\left(2x-1\right)\)
\(\Leftrightarrow\dfrac{-2}{3}x+\dfrac{1}{6}=\dfrac{2}{3}x-\dfrac{1}{3}\)
\(\Leftrightarrow\dfrac{-2}{3}x-\dfrac{2}{3}x=\dfrac{-1}{3}-\dfrac{1}{6}\)
\(\Leftrightarrow\dfrac{-4}{3}x=\dfrac{-1}{2}\)
\(\Leftrightarrow x=\dfrac{3}{8}\)
Vậy \(x=\dfrac{3}{8}\)
|\(\left|x+\frac{1}{3}\right|+\left|x+\frac{4}{3}\right|=\frac{9}{2}.x\) (1)
+)Xét \(x< -\frac{4}{3}\);(1) trở thành: \(-2x-\frac{5}{3}=\frac{9}{2}x\Leftrightarrow\frac{13}{2}x=-\frac{5}{3}\Leftrightarrow x=-\frac{10}{39}\)(loại)
+)Xét \(-\frac{4}{3}\le x< -\frac{1}{3}\);(1) trở thành: \(\frac{9}{2}x=1\Leftrightarrow x=\frac{2}{9}\) (loại)
+)Xét \(x>-\frac{1}{3}\);(1) trở thành: \(2x+\frac{5}{3}=\frac{9}{2}x\Leftrightarrow\frac{5}{2}x=\frac{5}{3}\Leftrightarrow x=\frac{2}{3}\) (chọn)
1/2x + 1/5 = 2/3x - 1/4
=> 1/2x - 2/3x = -1/4 - 1/5
=> -1/6x = -9/20
=> x = -9/20 : (-1/6)
=> x = 27/10
\(\frac{1}{2}x+\frac{1}{5}=\frac{2}{3}x-\frac{1}{4}\)
\(\frac{1}{2}x=\frac{2}{3}x-\frac{1}{4}-\frac{1}{5}\)
\(\frac{1}{2}x=-\frac{9}{20}+\frac{2x}{3}\)
\(\frac{1}{2}x=-\frac{9}{20}+\frac{2x}{3}-\frac{2x}{3}\)
\(-\frac{x}{6}=-\frac{9}{20}\)
\(6\left(-\frac{x}{6}\right)=6\left(-\frac{9}{20}\right)\)
\(-x=-\frac{27}{10}\)
\(\Rightarrow x=-\frac{27}{10}\)
x4 - 3x + 2 = (x4 - x3) + (x3 - x2) + (x2 - x) + (-2x + 2)
= (x - 1)(x3 + x2 + x - 2)
Bài 1:
a) \(x.\dfrac{3}{4}=\dfrac{9}{14}\)
\(\Rightarrow x=\dfrac{9}{14}:\dfrac{3}{4}\)
\(\Rightarrow x=\dfrac{6}{7}\)
b) \(x:\dfrac{5}{9}=\dfrac{3}{10}\)
\(\Rightarrow x=\dfrac{3}{10}.\dfrac{5}{9}\)
\(\Rightarrow x=\dfrac{1}{6}\)
\(\Leftrightarrow\left(x+1+x-1\right)\left(x+1-x+1\right)-3\left(x^2-1\right)=4\)
\(\Leftrightarrow2x.2-3x^2+3=4\)
\(\Leftrightarrow-3x^2-4x-1=0\)
\(\Leftrightarrow-3x^2-3x-x-1=0\)
\(\Leftrightarrow-3x\left(x+1\right)-\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(-3x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=-1\\x=-\frac{1}{3}\end{cases}}\)
Ta có x - 3/4=1/2
Suy ra x = 1/2 +3/4
Suy ra x = 5/4
x-3/4=1/2
x=1/2+3/4
x=5/4
chúc bạn học tốt !!!