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\(\Leftrightarrow x\left(3x+2\right)+\left(x+1\right)^2-\left(2x-5\right)\left(2x+5\right)=-12\)

\(\Leftrightarrow3x^2+2x+x^2+2x+1-4x^2+25=-12\)

\(\Leftrightarrow4x+26=-12\)

\(\Leftrightarrow4x=-38\)

\(\Leftrightarrow x=-\frac{19}{2}\)

Vậy tập nghiệm của phương trình là \(S=\left\{-\frac{19}{2}\right\}\)

SAI GẦN HẾT

a) Ta có: \(\dfrac{x+5}{3x-6}-\dfrac{1}{2}=\dfrac{2x-3}{2x-4}\)

\(\Leftrightarrow\dfrac{2\left(x+5\right)}{6\left(x-2\right)}-\dfrac{3\left(x-2\right)}{6\left(x-2\right)}=\dfrac{3\left(2x-3\right)}{6\left(x-2\right)}\)

Suy ra: \(2x+5-3x+6=6x-9\)

\(\Leftrightarrow-x+11-6x+9=0\)

\(\Leftrightarrow20-7x=0\)

\(\Leftrightarrow7x=20\)

hay \(x=\dfrac{20}{7}\)(thỏa ĐK)

Vậy: \(S=\left\{\dfrac{20}{7}\right\}\)

tìm x à                    

|3x-4|+3x+5=0

\(3x\left(x-5\right)-3x^2=3x+8\)

<=>  \(3x^2-15x-3x^2=3x+8\)

<=>  \(18x=-8\)

<=>  \(x=-\frac{4}{9}\)

Vậy....

\(a,x^3+3x^2=4x+12\)

\(x^2\left(x+3\right)=4\left(x+3\right)\)

\(\Rightarrow\left(x+3\right)\left(x^2-4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+3=0\\x^2-4=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-3\\x=\pm2\end{cases}}\)

\(b,49x^2=\left(3x+2\right)^2\)

\(7x=3x+2\)

\(\Rightarrow7x-3x=2\)

\(\Rightarrow4x=2\)

\(\Rightarrow x=\frac{1}{2}\)

các câu còn lại tương tự nha

\(a,x^3+3x^2=4x+12\)

\(x^3+3x^2-4x-12=0\)

\(\Rightarrow x^2\left(x+3\right)-4\left(x+3\right)=0\)

\(\Rightarrow\left(x+3\right)\left(x^2-4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+3=0\\\left(x+2\right)\left(x-2\right)=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-3\\x=\pm2\end{cases}}\)

\(b,49x^2=\left(3x+2\right)^2\)

\(\Rightarrow\left(7x\right)^2=\left(3x+2\right)^2\)

\(\Rightarrow7x=3x+2\)

\(\Rightarrow7x-3x=2\)

\(\Rightarrow4x=2\)

\(\Rightarrow x=\frac{1}{2}\)

\(c,3x^2\left(x-5\right)+12\left(5-x\right)=0\)

\(3x^2\left(x-5\right)-12\left(x-5\right)=0\)

\(\left(x-5\right)\left(3x^2-12\right)=0\)

\(\Rightarrow3.\left(x-5\right)\left(x^2-4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-5=0\\x^2-4=0\end{cases}\Rightarrow\orbr{\begin{cases}x=5\\x=\pm2\end{cases}}}\)

\(d,x^2\left(x-5\right)+45-9x=0\)

\(x^2\left(x-5\right)+9\left(5-x\right)=0\)

\(x^2\left(x-5\right)-9\left(x-5\right)=0\)

\(\left(x-5\right)\left(x^2-9\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-5=0\\x^2-9=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=5\\x=\pm3\end{cases}}\)

a) 

<=> 3x - 3 + x - 2 = 2x - 2 - x + 1

<=> 3x + x - 2x + x = -2 + 1 + 3 + 2

<=>    3x               = 4

<=>   x                  = 4/3

Các câu sau làm tương tự

\(\left(3x-3\right)+\left(x-2\right)=\left(2x-2\right)-\left(x-1\right)\)

<=>   \(3x-3+x-2=2x-2-x+1\)

<=>  \(4x-5=x-1\)

<=> \(3x=4\)

<=>  \(x=\frac{4}{3}\)

Vậy....

a) ĐKXĐ: \(x\notin\left\{\dfrac{1}{3};-\dfrac{1}{3}\right\}\)

Ta có: \(\dfrac{12}{1-9x^2}=\dfrac{1-3x}{1+3x}-\dfrac{1+3x}{1-3x}\)

\(\Leftrightarrow\dfrac{\left(1-3x\right)^2}{\left(1+3x\right)\left(1-3x\right)}-\dfrac{\left(1+3x\right)^2}{\left(1-3x\right)\left(1+3x\right)}=\dfrac{12}{\left(1-3x\right)\left(1+3x\right)}\)

Suy ra: \(9x^2-6x+1-9x^2-6x-1=12\)

\(\Leftrightarrow-12x=12\)

hay x=-1(thỏa ĐK)

Vậy: S={-1}

`@` `\text {Ans}`

`\downarrow`

`a)`

\(-5(x^2 - 3x +1 ) + x ( 1+5x ) =x-2 \)

`=> -5x^2 + 15x - 5 + x + 5x^2 = x - 2`

`=> (-5x^2 + 5x^2) + (15x + x) - 5 = x - 2`

`=> 16x - 5 = x - 2`

`=> 16x - 5 - x + 2 = 0`

`=> (16x - x) + (-5+2) = 0`

`=> 15x - 3 = 0`

`=> 15x = 3`

`=> x = 3 \div 15`

`=> x =`\(\dfrac{1}{5}\)

Vậy, `x =`\(\dfrac{1}{5}\)

`b)`

\(-4x (x-5) +7x (x-4) -3x^2 =12\)

`=> -4x^2 + 20x + 7x^2 - 28x - 3x^2 = 12`

`=> (-4x^2 - 3x^2 + 7x^2) + (20x - 28x) = 12`

`=> -8x = 12`

`=> x = 12 \div (-8)`

`=> x = `\(-\dfrac{3}{2}\)

Vậy, `x =`\(-\dfrac{3}{2}\)

`@` `\text {Kaizuu lv uu}`

Dễ thế mà không làm được