Answer:
x = -2 0r x = 6
Step-by-step explanation:
from the question
X² – 4x – 12=0
solve by completing the square method
we have;
X² – 4x – 12=0
X² – 4x = 12
to make the left hand side a perfect square we add 4 to both sides.
X² -4x + 4 = 12 + 4
X² -4x + 4 = 16
from left hand side X² -4x + 4
= (x -2) × ( x -2)
it can be simply expressed as
( x-2)²
so since X² -4x + 4 has been simplified to be ( x-2)²
then,
( x-2)² = 16
x - 2 = √ 16
since square root has two values it can either be positive or negative
so we have
x = 2 + √16
or
x = 2 - √16
therefore
x = 2 + √16
x = 2 + 4
x = 6
0r
x = 2 - 4
x = -2
