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\(a.2x-3=4x+6\)
\(\Leftrightarrow2x-3-4x-6=0\)
\(\Leftrightarrow-2x-9=0\)
\(\Leftrightarrow x=\dfrac{9}{2}\)
\(S=\left\{\dfrac{9}{2}\right\}\)
\(b.x\left(x-1\right)+x\left(x+3\right)=0\)
\(\Leftrightarrow x^2-x+x^2+3x=0\)
\(\Leftrightarrow2x^2+2=0\)
\(\Leftrightarrow x\left(2x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\2x+2=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)
\(S=\left\{0,-1\right\}\)
Mấy câu khác bn gửi lại đc ko tại mik chx hiểu lắm
a: =>-2x=9
=>x=-9/2
c: =>x(x-1+x+3)=0
=>x(2x+2)=0
=>x=0 hoặc x=-1
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,2x-3=4x+6\)
\(\Leftrightarrow2x-4x=6+3\)
\(\Leftrightarrow-2x=9\)
\(\Leftrightarrow x=-\dfrac{9}{2}\)
\(b,\) Ghi vậy mình không làm được.
\(c,\)\(x\left(x-1\right)+x\left(x+3\right)=0\)
\(\Leftrightarrow x\left(x-1+x+3\right)=0\)
\(\Leftrightarrow x\left(2x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\2x+2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)
\(d,\dfrac{x}{2x-6}-\dfrac{x}{2x+2}=\dfrac{2x}{\left(x+1\right)\left(x-3\right)}\)
\(\Leftrightarrow\dfrac{x}{2\left(x-3\right)}-\dfrac{x}{2\left(x+1\right)}-\dfrac{2}{\left(x+1\right)\left(x-3\right)}=0\left(dkxd:x\ne-1;x\ne3\right)\)
\(\Leftrightarrow\dfrac{x\left(x+1\right)-x\left(x-3\right)-2.2}{2\left(x+1\right)\left(x-3\right)}=0\)
\(\Leftrightarrow x^2+x-x^2+3x-4=0\)
\(\Leftrightarrow4x-4=0\)
\(\Leftrightarrow x=1\left(tmdk\right)\)
Vậy \(S=\left\{1\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
2) \(x^3-6x^2+11x-6=0\)
\(\Leftrightarrow\)\(x^3-3x^2-3x^2+9x+2x-6=0\)
\(\Leftrightarrow\)\(\left(x-3\right)\left(x^2-3x+2\right)=0\)
\(\Leftrightarrow\)\(\left(x-3\right)\left(x-2\right)\left(x-1\right)=0\)
bn giải tiếp nha
3) \(x^3-4x^2+x+6=0\)
\(\Leftrightarrow\)\(x^3-3x^2-x^2+3x-2x+6=0\)
\(\Leftrightarrow\)\(\left(x-3\right)\left(x^2-x-2\right)=0\)
\(\Leftrightarrow\)\(\left(x-3\right)\left(x-2\right)\left(x+1\right)=0\)
lm tiếp nha
4) \(x^3-3x^2+4=0\)
\(\Leftrightarrow\)\(x^3+x^2-4x^2-4x+4x+4=0\)
\(\Leftrightarrow\)\(\left(x+1\right)\left(x^2-4x+4\right)=0\)
\(\Leftrightarrow\)\( \left(x+1\right)\left(x-2\right)^2=0\)
lm tiếp nha
Mk làm mẫu 1 bài cho nha !
1. <=> (x^3-x^2)+(5x^2-5x)+(6x-6) = 0
<=> (x-1).(x^2+5x+6) = 0
<=> (x-1).[(x^2+2x)+(3x+6)] = 0
<=> (x-1).(x+2).(x+3) = 0
<=> x-1=0 hoặc x+2=0 hoặc x+3=0
<=> x=1 hoặc x=-2 hoặc x=-3
Vậy ..............
Tk mk nha
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a: Ta có: \(2x\left(x-1\right)-2x^2=-6\)
\(\Leftrightarrow2x^2-2x-2x^2=-6\)
\(\Leftrightarrow x=3\)
b: Ta có: \(2x\left(x-3\right)+5\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(2x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{5}{2}\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1 :
a) (3+x)(x2-9)-(x-3)(x2+3x+9) = ( x-3)(x+3)2-(x-3)(x2+3x+9)
= (x-3) ( x2+6x+9 - (x2+3x+9)) = (x-3) . 3x = 3x(x-3)
Các câu còn lại mình sẽ gửi bạn sau nếu có thời gian
Nhấn đúng để ủng hộ mình :))
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(2x\left(x+1\right)-3-2x=5\)
\(\Leftrightarrow2x^2+2x-3-2x=5\)
\(\Leftrightarrow2x^2=8\)
\(\Leftrightarrow x^2=4=\left(-2\right)^2=2^2\)
\(\Rightarrow x=2;-2\)
b)\(2x\left(3x+1\right)+\left(4-2x\right)=7\)
\(\Leftrightarrow6x^2+2x+4-2x=7\)
\(\Leftrightarrow6x^2+4=7\)
\(\Leftrightarrow6x^2=3\)
\(\Leftrightarrow x^2=\frac{1}{2}=-\sqrt{\frac{1}{2}}=\sqrt{\frac{1}{2}}\)
c)\(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x-1\right)^2=6\)
\(\Leftrightarrow x^3-9x^2+27x-27-x^3+27+6\left(x^2-2x+1\right)=6\)
\(\Leftrightarrow-3x^2+27x+6x^2-12x+6=6\)
\(\Leftrightarrow-3x^2+27x+6x^2-12x+6=6\)
\(\Leftrightarrow3x^2+15x=0\)
\(\Leftrightarrow3x\left(x+5\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x=0\\x+5=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\dfrac{x-3}{4}+\dfrac{2x-1}{3}=-\dfrac{x}{6}\)
\(\Leftrightarrow\dfrac{3\left(x-3\right)+4\left(2x-1\right)+2x}{12}=0\)
\(\Leftrightarrow3x-9+8x-4+2x=0\)
\(\Leftrightarrow13x-13=0\)
\(\Leftrightarrow13x=13\)
\(\Leftrightarrow x=1\)
\(b,\left(x-3\right)\left(2x-1\right)=\left(2x-1\right)\left(2x+3\right)\)
\(\Leftrightarrow\left(x-3\right)\left(2x-1\right)-\left(2x-1\right)\left(2x+3\right)=0\)
\(\Leftrightarrow\left(2x-1\right)\left(x-3-2x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\-x-6=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-6\end{matrix}\right.\)
x -2x = 6+3
x=9
\(x-6=3+2x\)
\(\Rightarrow x-2x=3+6\)
\(\Rightarrow x\left(1-2\right)=9\)
\(\Rightarrow x.\left(-1\right)=9\)
\(\Rightarrow x=9:\left(-1\right)\)
\(\Rightarrow x=-9\)