8756783678-3165223676=5591560002

cau tra loi la 50000 dong

6 con bam no 00

216 yo

\(a^2+11a+28=0\)

\(\Rightarrow a^2+7a+4a+28=0\)

\(\Rightarrow a\left(a+7\right)+4\left(a+7\right)=0\)

\(\Rightarrow\left(a+7\right)\left(a+4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}a+7=0\\a+4=0\end{cases}}\Rightarrow\orbr{\begin{cases}a=-7\\a=-4\end{cases}}\)