a = √5 - 1/2,b = √5 + 1/2
a² + b² + 7
= (a + b)² - 2ab + 7
= (2√5)² - 2(√5 - 1/2)(√5 + 1/2) + 7
= 20 - (5² - 1/2²) + 7
= 9/4
√(a² + b² + 7) = √(9/4) = 3/2
a = √5 - 1/2,b = √5 + 1/2
a² + b² + 7
= (a + b)² - 2ab + 7
= (2√5)² - 2(√5 - 1/2)(√5 + 1/2) + 7
= 20 - (5² - 1/2²) + 7
= 9/4
√(a² + b² + 7) = √(9/4) = 3/2