Answer:
3(x+2)² - 1
Explanation:
You have to complete the square and when you complete the square, the coefficient of x must be always 1. But here it's 3. So we need to take 3 out and put the x ones in brackets.
3x² + 12x + 11 = 3 [ x² + 4x ] + 11 = 3 [ (x+2)² - 4 ] + 11 = 3(x+2)² - 12 + 11 = 3(x+2)² - 1
Yup (3) is good for num 4