Question

y^2+5y+6=0

Answer 1

\(y^2+5y+6=0\\ \Leftrightarrow y^2+2y+3y+6=0\\ \Leftrightarrow\left(y^2+2y\right)+\left(3y+6\right)=0\\ \Leftrightarrow y\left(y+2\right)+3\left(y+2\right)=0\\ \Leftrightarrow\left(y+3\right)\left(y+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}y+3=0\\y+2=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}y=-3\\y=-2\end{matrix}\right.\)

Vậy phương trình có nghiệm \(S=\left\{-3;-2\right\}.\)

Answer 2

đề yc gì em?

Answer 3

\(y^2+5y+6=0\\ \Leftrightarrow y^2+3y+2y+6=0\\ \Leftrightarrow y\left(y+3\right)+2\left(y+3\right)=0\\ \Leftrightarrow\left(y+2\right).\left(y+3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}y+2=0\\y+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}y=-2\\y=-3\end{matrix}\right.\)

Vậy pt có tập nghiệm A={-2;-3}

Answer 4

y² + 5y + 6 = 0

⇔ y² + 2y + 3y + 6 = 0

⇔ (y² + 2y) + (3y + 6) = 0

⇔ y(y + 2) + 3(y + 2) = 0

⇔ (y + 2)(y + 3) = 0

⇔ y + 2 = 0 hoặc y + 3 = 0

*) y + 2 = 0

⇔ y = -2

*) y + 3 = 0

⇔ y = -3

Vậy S = {-3; -2}