Answer:
We must add number 36 to complete the square.
Step-by-step explanation:
Given : x² + 12x = -3.
To find : What number must you add to complete the square.
Solution : We have given that
x² + 12x = -3.
Step 1) On multiplying and divide by 2 the term 12 x
x² + 2 *x = -3.
x² + 2 * 6x = -3.
Step 2 ) Now add and subtracting square of 6 on left side.
x² + 2 * 6x + 6² - 6² = -3.
x² + 2 * 6x + 6² - 36 = -3.
We can see first three terms are complete square
(x + 6 )² - 36 = -3 .
On adding both side by 36
(x + 6 )² = - 3 + 36
(x + 6 )² = 33.
Therefore, We must add number 36 to complete the square.