What number must you add to complete the square x^2+12x =16 a. 24 b. 12 c. 6 d. 36

D. 36

Step-by-step explanation:

The square of half the x-coefficient must be added. That value is (12/2)² = 36.

You're trying to create a trinomial of the form ...

... (a + b)² = a² +2ab +b²

where a = x, and 2b = 12.

The number you need to add is b² = (2b/2)² = (12/2)² = 36.

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.