Dễ ợt:

 Thực hiện phép nhân một đơn thức với một đa thức ta được:

     \(6x-3-3x^2+2x=3x-3x^2+2\)

Thực hiện qui tắc chuyển vế đổi dấu ta được:

   \(6x+2x-3x-3x^2+3x^2=2+3\)

  \(x\left(6+2-3\right)=5\)

 \(x.5=5\) => x=1

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

\(\Leftrightarrow3x^2+3x-2x^2-4x=1-x\)

\(\Leftrightarrow x^2-1=0\)

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

\(b,\)\(\frac{1}{3}x^2-4x+2x\left(2-3x\right)=0\)

\(\Leftrightarrow\frac{1}{3}x^2-4x+4x-6x^2=0\)

\(\Leftrightarrow-\frac{17}{3}x^3=0\)

\(\Leftrightarrow x=0\)

3/4x + 5-(2/3x-4)-(1/6+1)=(1/3x+4)-(1/3x-3)

=3/4x+5-2/3x-4-1/6x+1=1/3x+4-1/3x-3

=-1/12=7

x=84

Đ/S...

x^3 - 3x^2 + 3x - 1 = 0

( x- 1)^3    = 0 

=> x -1 = 0

=> x = 1

\(c.\:\left(3x+4\right)^2-\left(3x+1\right)\left(3x-1\right)\\ =9x^2+24x+16-9x^2+1\\ 40x=-1\\ x=-\dfrac{1}{40}\)

\(d.\:\left(3x-1\right)^2-\left(3x-2\right)^2=0\\ \left(3x-1+3x-2\right)\left(3x-1-3x+2\right)=0\\ \left(6x-3\right)=0\\ x=\dfrac{1}{2}\)

\(g.\:\left(2x+1\right)^2-\left(x-1\right)^2=0\\ \left(2x+1+x-1\right)\left(2x+1-x+1\right)=0\\ 3x\left(x+2\right)=0\\ \Rightarrow\left[{}\begin{matrix}3x=0\\x+2=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\)

c,\(\left(3x+4\right)^2-\left(3x-1\right)\left(3x+1\right)=49\)

\(\Rightarrow9x^2+24x+16-\left(9x^2-1\right)=49\)

\(\Rightarrow9x^2+24x+16-9x^2+1=49\)

\(\Rightarrow24x=49-1-16\)

\(\Rightarrow24x=32\Rightarrow x=\dfrac{4}{3}\)

d, \(\left(3x-1\right)^2-\left(3x-2\right)^2=0\)

\(\Rightarrow\left(3x-1-3x+2\right).\left(3x-1+3x-2\right)=0\)

\(\Rightarrow6x-3=0\Rightarrow6x=3\Rightarrow x=\dfrac{1}{2}\)

e, \(\left(2x+1\right)^2-\left(x-1\right)^2=0\)

\(\Rightarrow\left(2x+1-x+1\right)\left(2x+1+x-1\right)=0\)

\(\Rightarrow\left(x+2\right).3x=0\Rightarrow x.\left(x+2\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x+2=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\)

Chúc bạn học tốt!!!

a)3x(x-1)+x-1=0

=>(x-1).(3x+1)=0

=>x-1=0  =>x=1

hoặc 3x+1=0  =>3x=-1   =>x=-1/3

b) dấu ngoặc thứ 2 đâu