Đặt \(x^2-2x+3=t\Rightarrow2x-x^2+6=9-t\)

Pt trở thành:

\(t\left(9-t\right)=18\Leftrightarrow t^2-9t+18=0\)

\(\Rightarrow\left[{}\begin{matrix}t=3\\t=6\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x^2-2x+3=3\\x^2-2x+3=6\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x=0\\x^2-2x-3=0\end{matrix}\right.\) (bấm máy)

\(2x\left(x+4\right)-2x^2-6=18\)

\(2x^2+8x-2x^2=18+6\)

\(8x=24\)

\(x=3\)

a) Ta có: \(\left(2x-5\right)^3=216\)

\(\Leftrightarrow2x-5=6\)

\(\Leftrightarrow2x=11\)

hay \(x=\dfrac{11}{2}\)

b) Ta có: \(2x-3⋮x+4\)

\(\Leftrightarrow-11⋮x+4\)

\(\Leftrightarrow x+4\in\left\{1;-1;11;-11\right\}\)

hay \(x\in\left\{-3;-5;7;-15\right\}\)

Alo, sugeni two wai phem. Si ga no, you woo be the me that nas te, ai gi da

(2x-6)(2x-18)=0

\(\Rightarrow\hept{\begin{cases}2x-6=0\\2x-18=0\end{cases}}\Rightarrow\hept{\begin{cases}2x=6\\2x=18\end{cases}}\Rightarrow\hept{\begin{cases}x=3\\x=9\end{cases}}\)

Vậy ...

2x-6.18

2x-108

x=108:2

x=54

a) \(2x\left(3x+1\right)+3x\left(4-2x\right)=7\)

\(\Rightarrow6x^2+2x+12x-6x^2=7\)

\(\Rightarrow14x=7\Rightarrow x=\frac{1}{2}\)

b) \(4\left(18-5x\right)-12\left(3x-7\right)=15\left(2x-16\right)-6\left(x+14\right)\)

\(72-20x-36x+84=30x-240-6x-84\)

\(\Rightarrow-20x-36x-30x+6x=-240-84-72-84\)

\(-80x=-480\)

x = 6

c) \(\left(3x+2\right).\left(2x+9\right)-\left(x+2\right).\left(6x+1\right)=\left(x+1\right)-\left(x-6\right)\)

\(\Rightarrow6x^2+4x+27x+18-6x^2-12x-x-2=x+1-x+6\) ( chỗ này bn tự phân tích ik nha, mk chỉ đưa ra kp sau khi phân tích thôi, ko thì viết ra dài lắm)

\(\Rightarrow18x+16=7\)

18x = -9

x = -2

18x = 

x + 18 = 6 - 2x

x + 2x = 6 - 18

3x = - 12

x = -4 

=.= hk tốt!!

x+2x = 6 - 18

3x = -12

x = -12 : 3

x = -4

Vậy......