PLEASE HELP ME WITH THIS QUESTIONPLEASE EXPLAIN

y = 2x² - 32x + 56 
y = 2(x² - 16x + 28)
y = 2(x² - 16x + 8² - 8² + 28)
y = 2( (x - 8)² -36)
y = 2(x - 8)² - 72

The equation can be rewritten as y = 2(x - 8)² - 72

The x-coordinate of the minimum is 8