5 ( x - 1 ) - 7 ( x - 2 ) = 2x - 39

<=> 5x - 5 - 7x + 14 = 2x - 39

<=> 5x - 7x - 2x = -39 + 5 - 14

<=> -4x = -48

<=> x = 12

x - 3 - 14.( x-2 )= -3x -3\(\Rightarrow\chi-3-28-14\chi-28=-3\chi-3\)

\(\Rightarrow\chi-3-28+3=-3\chi-3\)

\(\Rightarrow\chi-28=11\chi\)

\(\Rightarrow\chi-11\chi=28\)

\(\Rightarrow10\chi=28\Rightarrow\chi=2,8\left(kot.m\chi\inℤ\right)\) 

đề bài bị lỗi :(

a.\(2x^2+5x+8+\sqrt{x}=x^2+3x+35+x^2+2x-7\)

\(=2x^2+5x+8+\sqrt{x}=2x^2+5x+28\Leftrightarrow\sqrt{x}=20\Leftrightarrow x=400.\)

b.\(3\sqrt{x}+7x+5=\sqrt{x}+4x-6+3x+18\)

\(=3\sqrt{x}+7x+5=\sqrt{x}+7x+12\Leftrightarrow2\sqrt{x}=7\Leftrightarrow x=\frac{49}{4}.\)

c.\(8\sqrt{x}+2x-9=5x+7+6\sqrt{x}-3x-12.\)

\(=8\sqrt{x}+2x-9=2x+6\sqrt{x}-5\Leftrightarrow2\sqrt{x}=4\Leftrightarrow x=4.\)

d.\(2\sqrt{3x}+11x-18=5x+3+6\sqrt{3x}+6x-21\)

\(=2\sqrt{3x}+11x-18=11x+6\sqrt{3x}-19\Leftrightarrow4\sqrt{3x}=1\)

\(\Leftrightarrow\sqrt{3x}=\frac{1}{4}\Leftrightarrow3x=\frac{1}{16}\Leftrightarrow x=\frac{1}{48}.\)

a) \(2x^2+5x+8+\sqrt{x}=x^2+3x+35+x^2+2x-7\)

<=> \(2x^2+5x+8+\sqrt{x}=2x^2+5x+28\)

<=> \(2x^2+5x+8+\sqrt{x}-\left(2x^2+5\right)=28\)

<=> \(\sqrt{x}+8=28\)

<=> \(\sqrt{x}=28-8\)

<=> \(\sqrt{x}=20\)

<=> \(\left(\sqrt{x}\right)^2=20^2\)

<=> x = 400

=> x = 400

b) \(3\sqrt{x}+7x+5=\sqrt{x}+4x-6+3x+18\)

<=> \(3\sqrt{x}+7x+5=7x+\sqrt{x}+12\)

<=> \(3\sqrt{x}+5=7x+\sqrt{x}+12-7x\)

<=> \(3\sqrt{x}+5=\sqrt{x}+12\)

<=> \(3\sqrt{x}=\sqrt{x}+12-5\)

<=> \(3\sqrt{x}=\sqrt{x}+7\)

<=> \(3\sqrt{x}-\sqrt{x}=7\)

<=> \(2\sqrt{x}=7\)

<=> \(\sqrt{x}=\frac{7}{2}\)

<=> \(\left(\sqrt{x}\right)^2=\left(\frac{7}{2}\right)^2\)

<=> \(x=\frac{49}{4}\)

=> \(x=\frac{49}{4}\)

c) \(8\sqrt{x}+2x-9=5x+7+6\sqrt{x}-3x-12\)

<=> \(8\sqrt{x}+2x-9=2x+6\sqrt{x}-5\)

<=> \(8\sqrt{x}-9=2x+6\sqrt{x}-5-2x\)

<=> \(8\sqrt{x}-9=6\sqrt{x}-5\)

<=> \(8\sqrt{x}=6\sqrt{x}-5+9\)

<=> \(8\sqrt{x}=6\sqrt{x}+4\)

<=> \(8\sqrt{x}-6\sqrt{x}=4\)

<=> \(2\sqrt{x}=4\)

<=> \(\sqrt{x}=2\)

<=> \(\left(\sqrt{x}\right)^2=2^2\)

<=> x = 4

=> x = 4

d) \(2\sqrt{3x}+11x-18=5x+3+6\sqrt{3x}+6x-21\)

<=> \(2\sqrt{3x}+11x-18=11x+6\sqrt{3x}-18\)

<=> \(2\sqrt{3x}+11x-18-\left(11x-18\right)=6\sqrt{3x}\)

<=>\(2\sqrt{3x}=6\sqrt{3x}\)

<=> \(2\sqrt{3x}-6\sqrt{3x}=0\)

<=>\(-4\sqrt{3x}=0\)

<=> \(\sqrt{3x}=0\)

<=> \(\left(\sqrt{3x}\right)^2=0^2\)

<=> 3x = 0

<=> x = 0

=> x = 0

a) \(|3x-1|=|x+3|\)

\(\Leftrightarrow\orbr{\begin{cases}3x-1=x+3\\-3x+1=x+3\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=4\\-2x=2\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=2\\x=-1\end{cases}}}\)

Vậy x={2;-1}

b) \(|x-1|+3x=1\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=1-3x\\-x+1=1-3x\end{cases}\Leftrightarrow\orbr{\begin{cases}4x=2\\2x=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{1}{2}\\x=0\end{cases}}}\)

Vậy x={\(\frac{1}{2};0\)}

c) làm tương tự câu b)

b)\(\left|21x-5\right|=\left|3x-7\right|\)

\(\Leftrightarrow\begin{cases}21x-5=3x-7\\21x-5=7-3x\end{cases}\)

\(\Leftrightarrow\begin{cases}9x=-1\\24x=12\end{cases}\)

\(\Leftrightarrow\begin{cases}x=-\frac{1}{9}\\x=\frac{1}{2}\end{cases}\)

a)\(\left|2x-7\right|=3\)

\(\Rightarrow2x-7=\pm3\)

Nếu \(2x-7=3\)

\(\Rightarrow2x=10\)

\(\Rightarrow x=5\)

Nếu \(2x-7=-3\)

\(\Rightarrow2x=4\)

\(\Rightarrow x=2\)

à, phần a ra x = 400. Nhầm

\(\frac{3x-3}{7-x}=\frac{3}{5}\)

\(\frac{3\left(x-1\right)}{3}=\frac{7-x}{5}\)

\(x-1=\frac{7-x}{5}\)

\(5\left(x-1\right)=7-x\)

\(5x-5=7-x\)

\(5x+x=7+5\)

\(6x=12\)

\(x=2\)

\(\frac{3x-3}{7-x}=\frac{3}{5}\)

\(\Rightarrow\left(3x-3\right).5=\left(7-x\right).3\)

\(\Rightarrow15x-15=21-3x\)

\(\Rightarrow15x+3x=21+15\)

\(\Rightarrow18x=36\)

\(\Rightarrow x=2\)

\(|x-7|=|3x+3|\)

\(\Leftrightarrow\orbr{\begin{cases}x-7=3x+3\\x-7=-3x-3\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}-2x=10\\4x=-4\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=-5\\x=-1\end{cases}}\)

Vậy \(x\in\left\{-5;-1\right\}\)

\(\left|x-7\right|=\left|3x+3\right|\Leftrightarrow x-7=\pm\left(3x+3\right)\)

TH1:\(x-7=3x+3\Leftrightarrow3x-x=-7-3\)

\(\Leftrightarrow2x=-10\Rightarrow x=\frac{-10}{2}=-5\)

TH2:\(x-7=-3x-3\Leftrightarrow x+3x=7-3\)

\(\Leftrightarrow4x=4\Rightarrow x=\frac{4}{4}=1\)

                 Vậy\(x=-5;1\)

a) 2|2/3 - x| = 1/2

|2/3 - x| = 1/4

|2/3 - x| = 1/4 hoặc |2/3 - x| = -1/4

Xét 2 TH...