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

Multiple Choice

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

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