Tìm x biết :
a) -2×(x-1/3)-5× (x+1/3)=1/2×x
b) -(1/2×x-3/4)-(-x+1)=-3/2
Cảm ơn nhiều nha!
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a) \(\frac{3}{4}x-\frac{1}{4}=2\left(x-3\right)+\frac{1}{4}x\)
\(\frac{3}{4}x-\frac{1}{4}=2x-6+\frac{1}{4}x\)
\(\frac{3}{4}x-2x-\frac{1}{4}x=\frac{1}{4}-6\)
\(x\left(\frac{3}{4}-2-\frac{1}{4}\right)=-\frac{23}{4}\)
\(-\frac{3}{2}x=-\frac{23}{4}\)
\(x=-\frac{23}{4}\div\left(-\frac{3}{2}\right)\)
\(x=\frac{23}{6}\)
=> 20 - 4x - 3 - 3x = - 9
=> 17 - x = - 9
=> x = 26
Vậy x = 26
K mk nha
a) Cậu xem lại đề đi
b) \(3x.\left(x-2\right)-5x.\left(1-x\right)-8.\left(x^2-3\right)=4\)\(\Leftrightarrow3x^2-6x-5x+5x^2-8x^2+24-4=0\Leftrightarrow-11x+20=0\Leftrightarrow-11x=-20\Leftrightarrow x=\frac{20}{11}\)
c) \(2x^2+3.\left(x-1\right)\left(x+1\right)=5x\left(x+1\right)\Leftrightarrow2x^2+3\left(x^2-1\right)-5x\left(x+1\right)=0\)
\(\Leftrightarrow2x^2+3x^2-3-5x^2-5x=0\Leftrightarrow-5x=3\Leftrightarrow x=-\frac{3}{5}\)
Trần Anh: Cảm ơn bạn nhiều nhé :)) Phần a đúng là có sai đề pạn ạ mik làm hoài mà cux ko ra hì hì !!~~ Dù sao mik cux cảm ơn pạn nhiều nhiều nhé :3
\(-\left(\frac{1}{2}.x-\frac{3}{4}\right)-\left(-x+1\right)=-\frac{3}{2}\) \(\frac{3}{2}\)
<=> \(-\frac{1}{2}x+\frac{3}{4}+x-1=\frac{-3}{2}\)
<=> \(\frac{1}{2}x-\frac{1}{4}=\frac{-3}{2}\)
<=> \(\frac{1}{2}x=-\frac{5}{4}\)
<=> \(x=\frac{-5}{2}\)
\(-5.\left(2x-\frac{2}{5}\right)+\frac{1}{3}x.\left(-x+1\right)\) \(=-\frac{3}{2}\)
<=> \(-10x+2-\frac{x^2}{3}+\frac{1}{3}x\) \(=\frac{-3}{2}\)
làm nốt nha
mk phải đi học rồi
áp dụng các hằng đẳng thức thôi mà :)
a)\(x^2-2x+1=25\)
=>\(\left(x-1\right)^2=25\)
=>\(\orbr{\begin{cases}x-1=-5\\x-1=5\end{cases}}\)
b)\(3\left(x-1\right)^2-3x\left(x-5\right)=1\)
=>\(3\left[\left(x-1\right)^2-x\left(x-5\right)\right]=1\)
=>\(3\left(x^2-2x+1-x^2+5x\right)=1\)
=>\(3\left(3x+1\right)=1\)
=>\(3x+1=\frac{1}{3}\)
=>\(3x=\frac{-2}{3}\)
=>\(x=\frac{-2}{9}\)
c)\(\left(5-2x\right)^2-16=0\)
=>\(\left(5-2x\right)^2-4^2=0\)
=>\(\left(5-2x-4\right)\left(5-2x+4\right)=0\)
=>\(\orbr{\begin{cases}5-2x-4=0\\5-2x+4=0\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{9}{2}\end{cases}}}\)
a: \(\dfrac{x}{6}=\dfrac{8}{3}\)
=>\(x=6\cdot\dfrac{8}{3}=\dfrac{6}{3}\cdot8=8\cdot2=16\)
b: \(\dfrac{5}{x}=\dfrac{4}{9}\)
=>\(x=\dfrac{5\cdot9}{4}=\dfrac{45}{4}\)
c: \(\dfrac{x+3}{-4}=\dfrac{5}{20}\)
=>\(x+3=\dfrac{-4\cdot5}{20}=-1\)
=>x=-1-3=-4
d: \(\dfrac{7}{3+4x}=\dfrac{-2}{9}\)
=>\(4x+3=\dfrac{9\cdot7}{-2}=-\dfrac{63}{2}\)
=>\(4x=-\dfrac{63}{2}-3=-\dfrac{69}{2}\)
=>\(x=-\dfrac{69}{8}\)
f: ĐKXĐ: x<>1
\(\dfrac{3}{x-1}=\dfrac{x-1}{27}\)
=>\(\left(x-1\right)^2=3\cdot27=81\)
=>\(\left[{}\begin{matrix}x-1=9\\x-1=-9\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=10\left(nhận\right)\\x=-8\left(nhận\right)\end{matrix}\right.\)
a) \(-2\left(x-\dfrac{1}{3}\right)-5\left(x+\dfrac{1}{3}\right)=\dfrac{1}{2}x\)
\(\Leftrightarrow-2x+\dfrac{2}{3}-5x-\dfrac{5}{3}=\dfrac{1}{2}x\)
\(\Leftrightarrow-7x-1=\dfrac{1}{2}x\)
\(\Leftrightarrow-7x-\dfrac{1}{2}x=1\)
\(\Leftrightarrow-\dfrac{15}{2}x=1\)
\(\Leftrightarrow x=1:\left(-\dfrac{15}{2}\right)=-\dfrac{2}{15}\)
b) \(-\left(\dfrac{1}{2}x-\dfrac{3}{4}\right)-\left(-x+1\right)=\dfrac{3}{2}\)
\(\Leftrightarrow-\dfrac{1}{2}x+\dfrac{3}{4}+x-1=\dfrac{3}{2}\)
\(\Leftrightarrow\dfrac{1}{2}x-\dfrac{1}{4}=\dfrac{3}{2}\)
\(\Leftrightarrow\dfrac{1}{2}x=\dfrac{3}{2}+\dfrac{1}{4}=\dfrac{7}{4}\)
\(\Leftrightarrow x=\dfrac{7}{4}:\dfrac{1}{2}\)
\(\Leftrightarrow x=\dfrac{7}{2}\)
cảm ơn nha