Solve the System by the Substitution Method $$\begin{array} { l } y = 3 x ^ { 2 } + 6 x \\y = x ^ { 2 } - 4 x + 12\end{array}$$

Multiple Choice

Solve the system by the substitution method.
- $$\begin{array} { l } y = 3 x ^ { 2 } + 6 x \\y = x ^ { 2 } - 4 x + 12\end{array}$$

A) $( 1,9 ) , ( - 6,72 )$
B) $( 2,0 ) , ( - 3,9 )$
C) $( - 2,0 ) , ( - 3,9 )$
D) $( 2,0 ) , ( 3,45 )$