(2x + 12)^2

= (2x + 12)(2x + 12)

= 2x(2x + 12) + 12(2x + 12)

= 4x^2 + 24x + 24x + 144

= 4x^2 + 48x + 144

So we have

(2x + 12)^2 = 4x^2 + 48x + 144

Taking the square root of both sides, we get

2x + 12 = √(4x^2 + 48x + 144)

= (2x + 12)(2x + 12)

= 2x(2x + 12) + 12(2x + 12)

= 4x^2 + 24x + 24x + 144

= 4x^2 + 48x + 144

So we have

(2x + 12)^2 = 4x^2 + 48x + 144

Taking the square root of both sides, we get

2x + 12 = √(4x^2 + 48x + 144)