The First Question:
√8
Prime factorization of 8: 2³
= √2³
Apply radical rule: a^b+c = a^b * a^c
2³ = 2² * 2
=√2² * 2
Apply radical rule: √ab = √a√b, a ≥ 0, b ≥ 0
√2² * 2 = √2² √2
Apply radical rule: √a² = a, a ≥ 0
√2² = 2
2√2
The Third question:
√-8
Let's apply radical rule:
√-a = √-1 √