Question

Tìm x,y biết: (x-7)^8+ly^2-4l=0

 

help me!!!

Answer 1

Do \(\left(x-7\right)^8\ge0;\left|y^2-4\right|\ge0\)

 \(\Rightarrow\left(x-7\right)^8+\left|y^2-4\right|\ge0\)

Mà theo đề bài: (x - 7)⁸ + |y² - 4| = 0

=> \(\begin{cases}\left(x-7\right)^8=0\\\left|y^2-4\right|=0\end{cases}\)=> \(\begin{cases}x-7=0\\y^2-4=0\end{cases}\)=> \(\begin{cases}x=7\\y^2=4\end{cases}\)=> \(\begin{cases}x=7\\y\in\left\{2;-2\right\}\end{cases}\)