Tìm x biết (x-3)^3+3-x=0
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\(\left(x-3\right)\left(x+3\right)-\left(x-3\right)^2=0\Leftrightarrow\left(x-3\right)\left(x+3-x+3\right)=0\Leftrightarrow6\left(x-3\right)=0\Leftrightarrow x-3=0\Leftrightarrow x=3\)
Ta có: \(\left(x-3\right)\left(x+3\right)-\left(x-3\right)^2=0\)
\(\Leftrightarrow x^2-9-x^2+6x-9=0\)
\(\Leftrightarrow6x=18\)
hay x=3
Bài 1:
a)\(\begin{cases}\left(x-3\right)^2+\left(y+2\right)^2=0\\\begin{cases}\left(x-3\right)^2\ge0\\\left(y+2\right)^2\ge0\end{cases}\end{cases}\)
\(\Rightarrow\begin{cases}\left(x-3\right)^2=0\\\left(y+2\right)^2=0\end{cases}\)\(\Rightarrow\begin{cases}x=3\\y=-2\end{cases}\)
b) tương tự
b) (x-12+y)200+(x-4-y)200= 0
\(\begin{cases}\left(x-12+y\right)^{200}+\left(x-4-y\right)^{200}=0\\\begin{cases}\left(x-12+y\right)^{200}\ge0\\\left(x-4-y\right)^{200}\ge0\end{cases}\end{cases}\)
\(\Rightarrow\begin{cases}\left(x-12+y\right)^{200}=0\\\left(x-4-y\right)^{200}=0\end{cases}\)\(\Rightarrow\begin{cases}x-12+y=0\\x-4-y=0\end{cases}\)\(\Rightarrow\begin{cases}x+y=12\left(1\right)\\x-y=4\left(2\right)\end{cases}\)
Trừ theo vế của (1) và (2) ta được:
\(2y=8\Rightarrow y=4\)\(\Rightarrow\begin{cases}x+4=12\\x-4=4\end{cases}\)\(\Rightarrow x=8\)
Vậy x=8; y=4
\(a,\left(x+3\right)\left(x-3\right)+x\left(3-x\right)=0\)
\(\Rightarrow\left(x+3\right)\left(x-3\right)-x\left(x-3\right)=0\)
\(\Rightarrow\left(x-3\right)\left(x+3-x\right)=0\)
\(\Rightarrow3\left(x-3\right)=0\)
\(\Rightarrow x-3=0\)
\(\Rightarrow x=3\)
\(b,x\left(x-3\right)+x-3=0\)
\(\Rightarrow\left(x-3\right)\left(x+1\right)=0\)
\(\Rightarrow\hept{\begin{cases}x-3=0\\x+1=0\end{cases}\Rightarrow\hept{\begin{cases}x=3\\x=-1\end{cases}}}\)
Bài giải
\(\left(x-3\right)2-\left(x-3\right)\left(x+3\right)=0\)
\(\left(x-3\right)\left(x+3-2\right)=0\)
\(\left(x-3\right)\left(x+1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-3=0\\x+1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=-1\end{cases}}\)
\(\Rightarrow\text{ }x\in\left\{3\text{ ; }-1\right\}\)
\(\left(x-3\right).2-\left(x-3\right)\left(x+3\right)=0\Leftrightarrow\left(x-3\right)\left[2-\left(x+3\right)\right]=0\)
\(\Leftrightarrow\left(x-3\right)\left(2-x-3\right)=0\Leftrightarrow\left(x-3\right)\left[\left(-1\right)-x\right]\). Xét 2 trường hợp
Xét 2 trường hợp. \(TH1:x-3=0\Leftrightarrow x=0+3=3\)
\(TH2:\left(-1\right)-x=0\Leftrightarrow x=\left(-1\right)-0=-1\). Vậy \(x\in\left\{-1;3\right\}\)
a.\(x+3\sqrt{x}=0\)
\(ĐK:x\ge0\)
\(\Leftrightarrow\sqrt{x}\left(\sqrt{x}+3\right)=0\)
\(\Leftrightarrow x=0\) ( vì \(\sqrt{x}+3\ge3>0\) )
b.\(x-3\sqrt{x}=0\)
\(ĐK:x\ge0\)
\(\Leftrightarrow\sqrt{x}\left(\sqrt{x}-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)
\(x\left(x-3\right)^3+3-x=0\)
\(\Leftrightarrow x\left(x-3\right)^2-\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left[x\left(x-3\right)-1\ne0\right]=0\)
\(\Leftrightarrow x=3\)
ta có
\(\left(x-3\right)^3-\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left[\left(x-3\right)^2-1\right]=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\\left(x-3\right)^2-1=0\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}x=3\\\left(x-2\right)\left(x-4\right)=0\end{cases}}\)pt dưới \(\Leftrightarrow\orbr{\begin{cases}x=2\\x=4\end{cases}}\)
vậy x=2 hoặc x=3 hoặc x=4