express (6+2√ 5)² - (6 - 2√ 5)² in the form k√ 5?

Question

plzz help mee
im confused

tanx

Answer 1

a^2-b^2 = (a+b)(a-b)
(6+2sqrt(5))^2-(6-2sqrt(5))^2 =
(6 + 2sqrt(5) + 6 - 2sqrt(5))(6 + 2sqrt(5) - 6 + 2sqrt(5))
= (12)(4 sqrt(5)) = 48 sqrt(5)

Answer 2

I make it 24sqrt(5)

(36 +24sqrt(5)+40) - (36-24sqrt(5)+40)=48sqrt(5)

Answer 3

(6 + 2sqrt5)^2 - (6 - 2sqrt5)^2
(6 + 2sqrt5)(6 + 2sqrt5) - (6 - 2sqrt5)(6 - 2sqrt5)
36 +24sqrt5 + 20 - 36 +24sqrt5 - 20
48 sq rt 5
k = 24