Question

giai pt
x+y=15 \(\Omega\)
x.y=50 \(\Omega\)

Answer 1

\(x+y=15\Rightarrow y=15-x\)

Mà x.y=50 nên

\(x\left(15-x\right)=50\)\(\Leftrightarrow15x-x^2-50=0\)

\(\Leftrightarrow\left(10x-x^2\right)-\left(50-5x\right)\)\(\Leftrightarrow\left(10-x\right)\left(x-5\right)=0\)

<=>\(\left[{}\begin{matrix}x=10\\x=5\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}y=5\\y=10\end{matrix}\right.\)

vậy các cặp x,y cần tìm là (10;5);(5;10)