Question

ai giúp em tìm x với ạ 

Answer 1

\(\left(x+1\right)\left(x-2\right)\left(x^2-8x+15\right)=0\)

\(\Leftrightarrow\left(x+1\right)\left(x-2\right)\left(x-3\right)\left(x-5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x-2=0\\x-3=0\\x-5=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=2\\x=3\\x=5\end{matrix}\right.\)

\(\Rightarrow A=\left\{-1;2;3;5\right\}\)