Verified answer

2(a + 1)(b + 1)=(a + b )(a + b + 2)

2(ab + a + b + 1) = a² + ab + 2a + ab + b² + 2b

2ab + 2a + 2b + 2 = a² + ab + 2a + ab + b² + 2b

2ab + 2a + 2b + 2 - 2ab - 2a - 2b = a² + b²

a² + b² = 2