Answer:
Step 3: x² + 6x + 64 = -8 + 64
Explanation:
At step 3 add 64 on both sides to complete the square.
so x² + 6x = -8
becomes x² + 6x + 64 = -8 + 64 when 64 is added both sides giving us step 3.
continuing from there, we get
x² + 6x + 64 = 56
we then use a² + 2ab + b² = (a + b)² on the left side to get
(x + 8)² = 56 (solve the equation for x)
by taking the root on both sides
√(x + 8)² = √56
x + 8 = +- 2√14 (separate the equations
x + 8 = 2√14
x + 8 = -2√14
Solving for x
x = 2√14 - 8 or x = -2√14 - 8