câu này cần có điều kiện \(\left(x;y\in Z\right)\) mới tìm được

để mk lm với điều kiện \(\left(x;y\in Z\right)\) nha

ta có : \(\left(3x-\dfrac{1}{5}\right)^{200}+\left(\dfrac{2y}{5}+\dfrac{4}{7}\right)^{100}=100\)

\(\Leftrightarrow\left(3x-\dfrac{1}{5}\right)^{200}=100-\left(\dfrac{2y}{5}+\dfrac{4}{7}\right)^{100}\ge0\)

\(\Rightarrow\left(\dfrac{2y}{5}+\dfrac{4}{7}\right)^{100}\le100\) \(\Leftrightarrow\dfrac{-2\left(\sqrt[100]{100}-\dfrac{4}{7}\right)}{5}\le y\le\dfrac{2\left(\sqrt[100]{100}-\dfrac{4}{7}\right)}{5}\)

\(\Rightarrow y=0\left(y\in Z\right)\)

với \(y=0\) thì ta có : \(\left(3x-\dfrac{1}{5}\right)^{200}+\left(\dfrac{4}{7}\right)^{100}=100\)

\(\Rightarrow\left(3x-\dfrac{1}{5}\right)^{200}=100-\left(\dfrac{4}{7}\right)^{100}\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-\dfrac{1}{5}=\sqrt[200]{100-\left(\dfrac{4}{7}\right)^{100}}\\3x-\dfrac{1}{5}=-\sqrt[200]{100-\left(\dfrac{4}{7}\right)^{100}}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{\sqrt[200]{100-\left(\dfrac{4}{7}\right)^{100}}+\dfrac{1}{5}}{3}\\x=\dfrac{-\sqrt[200]{100-\left(\dfrac{4}{7}\right)^{100}}+\dfrac{1}{5}}{3}\end{matrix}\right.\)

vì 2 giá trị này \(\notin Z\) \(\Rightarrow x\in\varnothing\)

vậy phương trình vô nghiệm .

có nhầm đề k cậu?

x/4=y/3 nên x/20=y/15

y/5=z/3 nên y/15=z/9

=>x/20=y/15=z/9

Áp dụng tính chất của DTSBN, ta được:

\(\dfrac{x}{20}=\dfrac{y}{15}=\dfrac{z}{9}=\dfrac{x-y-z}{20-15-9}=\dfrac{-100}{-4}=25\)

=>x=500; y=375; z=225

(1)\(2^2.x+1=32\)

4.x = 32-1

4.x=31

x=31:4

x= 7,75

(4)\(\left(x-1\right)^3-2^5=7^2\)

\(\left(x-1\right)-32=49\)

\(\left(x-1\right)=49-32\)

\(x-1=17\)

x=17+1

x=18

\(\left(x-\frac{1}{5}\right)^{2004}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}=0\)

Ta có:

\(\left\{{}\begin{matrix}\left(x-\frac{1}{5}\right)^{2004}\ge0\\\left(y+0,4\right)^{100}\ge0\\\left(z-3\right)^{678}\ge0\end{matrix}\right.\forall x,y,z.\)

\(\Rightarrow\left(x-\frac{1}{5}\right)^{2004}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}\ge0\) \(\forall x,y,z.\)

\(\Rightarrow\left(x-\frac{1}{5}\right)^{2004}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}=0\)

\(\Rightarrow\left\{{}\begin{matrix}\left(x-\frac{1}{5}\right)^{2004}=0\\\left(y+0,4\right)^{100}=0\\\left(z-3\right)^{678}=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x-\frac{1}{5}=0\\y+0,4=0\\z-3=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0+\frac{1}{5}\\y=0-0,4\\z=0+3\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\frac{1}{5}\\y=-0,4\\z=3\end{matrix}\right.\)

Vậy \(\left(x;y;z\right)\in\left\{\frac{1}{5};-0,4;3\right\}.\)

Chúc bạn học tốt!

Giải:

Đặt \(\dfrac{x}{3}=\dfrac{y}{4}=\dfrac{z}{5}=k\Rightarrow\left\{{}\begin{matrix}x=3k\\y=4k\\z=5k\end{matrix}\right.\)

Ta co: \(2x^2+2y^2-3z^2=-100\)

\(\Rightarrow18k^2+32k^2-75k^2=-100\)

\(\Rightarrow-25k^2=-100\)

\(\Rightarrow k^2=4\)

\(\Rightarrow k=\pm2\)

+) \(k=2\Rightarrow x=6,y=8,z=10\)

+) \(k=-2\Rightarrow x=-6,y=-8,z=-10\)

Vậy bộ số \(\left(x;y;z\right)\) là \(\left(6;8;10\right);\left(-6;-8;-10\right)\)

Ta có: \(\dfrac{x}{3}=\dfrac{y}{4}=\dfrac{z}{5}\) => \(\dfrac{2x^2}{18}=\dfrac{2y^2}{32}=\dfrac{3z^2}{75}\)

Áp dụng tính chất của dãy tỉ số = nhau ta có:

\(\dfrac{2x^2}{18}=\dfrac{2y^2}{32}=\dfrac{3z^2}{75}\) = \(\dfrac{2x^2+2y^2-3z^2}{18+32-75}\) = \(\dfrac{-100}{-25}\) = 4

=> \(\left\{{}\begin{matrix}2x^2=72\\2y^2=128\\3z^2=300\end{matrix}\right.\) => \(\left\{{}\begin{matrix}x^2=36\\y^2=64\\z^2=100\end{matrix}\right.\) => \(\left\{{}\begin{matrix}x=\pm6\\y=\pm8\\z=\pm10\end{matrix}\right.\)

Vì x,y,z cùng dấu => (x;y;z)= (6;8;10); (-6;-8;-10)

Ta có :

\(\left(x-\dfrac{1}{5}\right)^{2014}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}=0\)

Mà \(\left\{{}\begin{matrix}\left(x-\dfrac{1}{5}\right)^{2014}\ge0\\\left(y+0,4\right)^{100}\ge0\\\left(z-3\right)^{678}\ge0\end{matrix}\right.\)

\(\Leftrightarrow\left(x-\dfrac{1}{5}\right)^{2014}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}\ge0\)

Lại có : \(\left(x-\dfrac{1}{5}\right)^{2014}+\left(y+0,4\right)^{100}+\left(z-3\right)^{678}=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left(x-\dfrac{1}{5}\right)^{2014}=0\\\left(y+0,4\right)^{100}=0\\\left(z-3\right)^{678}=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-\dfrac{1}{5}=0\\y+0,4=0\\z-3=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{5}\\y=-0,4\\z=3\end{matrix}\right.\)

Vậy ,,,

Ai giúp tui với coi ? 

thanks trước 

thanks trước 

Ai giúp tui với coi ? 

thanks trước 

thanks trước