For an arithmetic sequence $\left\{ a _ { n } \right\}$ with first term 2, $$2 \left( a _ { 2 } + a _ { 3 } \right) = a _ { 9 }$$ Find the common difference of the sequence $\left\{ a _ { n } \right\}$. [3 points]
For an arithmetic sequence $\left\{ a _ { n } \right\}$ with first term 2,
$$2 \left( a _ { 2 } + a _ { 3 } \right) = a _ { 9 }$$
Find the common difference of the sequence $\left\{ a _ { n } \right\}$. [3 points]