tìm các số x,y,z biết
\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2010}=0\)
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\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
\(\Rightarrow\left\{{}\begin{matrix}\left(3x-5\right)^{2006}=0\\\left(y^2-1\right)^{2008}=0\\\left(x-z\right)^{2100}=0\end{matrix}\right.\Leftrightarrow x=z=\dfrac{5}{3}\)
\(\Rightarrow\left[{}\begin{matrix}y=1\\y=-1\end{matrix}\right.\)
Từ đề suy ra :
\(\left\{{}\begin{matrix}\left(3x-5\right)^{2006}=0\\\left(y^2-1\right)^{2008}=0\\\left(x-z\right)^{2100}=0\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}3x-5=0\\y^2-1=0\\x-z=0\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}x=z=\dfrac{5}{3}\\y=\pm1\end{matrix}\right.\)
Ta có: \(\left(3x-5\right)^{2006}\ge0\)với mọi x
\(\left(y^2-1\right)^{2008}\ge0\)với mọi y
\(\left(x-z\right)^{2100}\ge0\) với mọi x,z
\(\Rightarrow\)\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}\ge0\)với mọi x
Mà \(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
\(\Rightarrow\left(3x-5\right)^{2006}=0;\left(y^2-1\right)^{2008}=0;\left(x-y\right)^{2100}=0\)
Xét:
\(\left(3x-5\right)^{2006}=0\hept{\begin{cases}3x-5=0\\3x=5\\x=\frac{5}{3}\end{cases}}\)
Xét:
\(\left(y^2-1\right)^{2008}=0\hept{\begin{cases}y^2-1=0\\y^2=1\\y=1hoac-1\end{cases}}\)
Xét:
\(\left(x-z\right)^{2100}=0\hept{\begin{cases}x-z=0\\\frac{5}{3}-z=0\\z=\frac{5}{3}\end{cases}}\)
\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
\(\Leftrightarrow\hept{\begin{cases}3x-5=0\\y^2-1=0\\x-z=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=z=\frac{5}{3}\\y=1\end{cases}}\)
\(\left(3x-5\right)^{2006}\ge0;\left(y^2-1\right)^{2008}\ge0;\left(x-z\right)^{2100}\ge0\) với mọi x,y,z
mà theo đề:......=0
\(\Rightarrow\left(3x-5\right)^{2006}=0\Rightarrow3x-5=0\Rightarrow3x=5\Rightarrow x=\frac{5}{3}\)
\(y^2-1=0\Rightarrow y^2=1\Rightarrow y\in\left\{-1;1\right\}\)
\(\left(x-z\right)^{2100}=0\Rightarrow x-z=0\Rightarrow x=z\Rightarrow z=\frac{5}{3}\)
vậy...
Ta có:
\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
Vì \(\left\{{}\begin{matrix}\left(3x-5\right)^{2006}\ge0\\\left(y^2-1\right)^{2008}\ge0\\\left(x-z\right)^{2100}\ge0\end{matrix}\right.\)
\(\Rightarrow\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(3x-5\right)^{2006}=0\\\left(y^2-1\right)^{2008}=0\\\left(x-z\right)^{2100}=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x-5=0\\y^2-1=0\\x-z=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{5}{3}\\y=\pm1\\z=\dfrac{5}{3}\end{matrix}\right.\)
Vậy ...
Chúc bạn học tốt!
a)\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2010}=0\)
\(\Leftrightarrow\left(3x-5\right)^{2006}=0\Leftrightarrow3x-5=0\Leftrightarrow x=\frac{5}{3}\)
hay\(\left(y^2-1\right)^{2008}=0\Leftrightarrow y^2-1=0\Leftrightarrow y^2=1\Leftrightarrow y=\pm1\)
hay\(\left(x-z\right)^{2010}=0\Leftrightarrow x-z=0\Leftrightarrow\frac{5}{3}-z=0\Leftrightarrow z=\frac{5}{3}\)
V...\(x=\frac{5}{3},y=\pm1,z=\frac{5}{3}\)
b)Ta co:\(\frac{x}{2}=\frac{y}{3}=\frac{z}{4}\Rightarrow\frac{x^2}{4}=\frac{y^2}{9}=\frac{z^2}{16}=\frac{x^2+y^2+z^2}{4+9+16}=\frac{116}{29}=4\)
Suy ra:\(\frac{x}{2}=4\Leftrightarrow x=8\)
\(\frac{y}{3}=4\Leftrightarrow y=12\)
\(\frac{z}{4}=4\Leftrightarrow z=16\)
V...
VÌ \(\left(x-1\right)^{2012}\ge0\)
\(\left(y-2\right)^{2010}\ge0\)
\(\left(x-z\right)^{2008}\ge0\)
nên dấu \(=\)xảy ra khi \(\hept{\begin{cases}x=z\\x=1\\y=2\end{cases}\Leftrightarrow\hept{\begin{cases}x=z=1\\y=2\end{cases}}}\)
Vì \(\left(3x-5\right)^{2006}\ge0\) ; \(\left(y^2-1\right)^{2008}\ge0\) ; \(\left(x-z\right)^{2100}\ge0\)
\(\Rightarrow\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}\ge0\)
Dấu " = " xảy ra \(\Leftrightarrow\hept{\begin{cases}3x-5=0\\y^2-1=0\\x-z=0\end{cases}\Leftrightarrow}\hept{\begin{cases}x=\frac{5}{3}\\y^2=1\\z=\frac{5}{3}\end{cases}}\)<=> x = z = 5/3 và y = 1 hoặc y = -1
Vậy....
\(\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
Ta có:
\(\hept{\begin{cases}\left(3x-5\right)^{2006}\ge0\\\left(y^2-1\right)^{2008}\ge0\\\left(x-z\right)^{2100}\ge0\end{cases}}\)
\(\Leftrightarrow\left(3x-5\right)^{2006}+\left(y^2-1\right)^{2008}+\left(x-z\right)^{2100}=0\)
Dấu "=" xảy ra:
\(\Leftrightarrow\hept{\begin{cases}3x-5=0\\y^2-1=0\\x-z=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}3x=5\\y^2=1\\x-z=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=\frac{5}{3}\\y=\pm1\\z=\frac{5}{3}\end{cases}}\)
Vây khi x = \(\frac{5}{3}\); y = \(\pm1\), z = \(\frac{5}{3}\)thì biểu thức trên có giá trị bằng 0.
Chúc em học tốt nhé!!!
Ta có \(\hept{\begin{cases}\left(3x-5\right)^{2008}\ge0\\\left(y^2-1\right)^{2010}\ge0\\\left(x-z\right)^{2012}\ge0\end{cases}}\)mà \(\left(3x-5\right)^{2008}+\left(y^2-1\right)^{2010}+\left(x-z\right)^{2012}=0\)
\(\Rightarrow\hept{\begin{cases}\left(3x-5\right)^{2008}=0\\\left(y^2-1\right)^{2010}=0\\\left(x-z\right)^{2012}=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}3x-5=0\\y^2-1=0\\x-z=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=\frac{5}{3}\\y=1;-1\\z=x=\frac{5}{3}\end{cases}}\)
a: =>|x-2009|=2009-x
=>x-2009<=0
=>x<=2009
b: =>2x-1=0 và y-2/5=0 và x+y-z=0
=>x=1/2 và y=2/5 và z=x+y=1/2+2/5=5/10+4/10=9/10