Question

[Toan Nguyen]

Tìm x biết a là hằng số

a²x + 3ax + 9 = a² (a khác 0 ; a khác -3 )

Answer 1

[Nguyễn Việt Hoàng]

\(a^2x+3ax+9=a^2\)

\(a^2x+3ax+9-a^2=0\)

\(ax\left(a+3\right)+\left(3-a\right)\left(a+3\right)=0\)

\(\left(a+3\right)\left(ax+3-a\right)=0\)

\(\left(a+3\right)\left[a\left(x-1\right)+3\right]=0\)

\(\Leftrightarrow\orbr{\begin{cases}a+3=0\\a\left(x-1\right)+3=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}a=-3\left(L\right)\\a=\left\{\pm1;3\right\}\left(N\right);a=-3\left(L\right)\end{cases}}\)

Vậy \(a=\left\{\pm1;3\right\}\)