help w/ square roots?

Question

Write in simpliest radical form (assume all variables are non-negative)

1] (5-2√3)^2

2] √5 (√10 -4√5)

Answer 1

(5-2√3)²
=5² - 2×5×2√3 + (2√3)²
= 25 - 20√3 + 2²×3
= 37 - 20√3

√5(√10 - 4√5)
= √50 - 4(√5)²
= √2√25 - 4×5
= 5√2 - 20

Answer 2

1] (5-2√3)(5-2√3)= 25-20√3+4*3= 37 - 20√3

2] √5 (√10 -4√5)= √50 -4√25= 5 √2 - 20

Answer 3

25 - 20√3 +12 = 37 - 20√3

√50 - 20 = 5√2 - 20