Determine the Constant That Should Be Added to the Binomial $$x ^ { 2 } + 18 x$$

Multiple Choice

Determine the constant that should be added to the binomial so that it becomes a perfect square trinomial. Then write
and factor the trinomial.
- $$x ^ { 2 } + 18 x$$

A) $324 ; x ^ { 2 } + 18 x + 324 = ( x + 18 ) ^ { 2 }$
B) $9 ; x ^ { 2 } + 18 x + 9 = ( x + 81 ) ^ { 2 }$
C) $18 ; x ^ { 2 } + 18 x + 18 = ( x + 324 ) ^ { 2 }$
D) $81 ; x ^ { 2 } + 18 x + 81 = ( x + 9 ) ^ { 2 }$