Question

(X^2+1)×(x+3)+5=(x-3)×(x+4)+10

Answer 1

\(\left(x^2+1\right)\left(x+3\right)+5=\left(x-3\right)\left(x+4\right)+10\)

\(\Leftrightarrow x^3+3x^2+x+3+5=x^2+x-12+10\)

\(\Leftrightarrow x^3+3x^2+x-x^2-x=-12+10-3-5\)

\(\Leftrightarrow x^2\left(x+2\right)=-10\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2=-10\\x+2=-10\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x\in\varnothing\\x=-12\end{matrix}\right.\)

sau khi dùng phép thử ta nhận thấy \(x\ne-12\)

Vậy \(x\in\varnothing\)