Use Square of Sum: (a + b)^2 = a^2 + 2ab + b^2
b^2 + 2b * 12 + 12^2
Simplify 12^2 to 144
b^2 + 2b * 12 + 144
Simplify 2b * 12 to 24b
b^2 + 24b + 144
