Answer:
The coefficient of the 2nd term of trinomial is 18.
Explanation:
You can expand in a faster way by using the formula, (a+b)² = a²+2ab+b² :
(3x+3)² = (3x)² + 2(3x)(3) + 3²
= 9a² + 18a + 9
OR
You can expand it by doing step by step :
(3x+3)² = (3x+3)(3x+3)
= 3x(3x) + 3x(3) + 3(3x) + 3(3)
= 9x² + 9x + 9x + 9
= 9x² + 18x + 9