Question

What is the product of (3+radical 5) and (3-radical 5)

Answer 1

(3 + √((5)) + (3 - √(5))
3(3 - √(5)) + √(5)(3 - √(5)))
3(3) - 3(√(5)) + √(5)(3) + √(5)(√(5))
9 - 3√(5) + 3√(5) - √(25)
9 - 5
4

Answer 2

(3 + $\sqrt{5}$) × (3 - $\sqrt{5}$)
Take the special case
(a - b)×(a + b)=a² - b²

a = 3
b = $\sqrt{5}$

3² - ($\sqrt{5}$)²     {(√)² = the number itself}
              9 - 5
                4