\(x^2+6x+11=0\)
\(x^2+2.x.3+9+2=0\)
\(x^2+2.x.3+3^2=-2\)
\(\left(x+3\right)^2=-2\)
Vì \(\left(x+3\right)^2\ge0\forall x\)
Mà\(-2< 0\)
\(\Rightarrow x\in\varnothing\)
\(x^2+6x+11=0\)
\(x\left(x+6\right)=-11\)
Ta có bảng:
x | 1 | -1 | 11 | -11 |
x+6 | -11 | 11 | -1 | 1 |
x | -17 | 5 | -7 | -5 |
Vậy..
hok tốt!!