Math Help! Simplifying Radicals? Let me know if there is a problem?

Question

√128x^3

√15a^8b

-3√150a^7 c^2

-√320y^9 z^10

Answer 1

Well, √128x^3 = √2(8^2)x(x^2) = 8x√2x.

The rest are similarly done.

Answer 2

I have assumed the entire expression is under the radical.

√128x^3 = √(64x^2)*√(2x) = 8x√(2x)

√15a^8b = a^4√(15b)

-3√150a^7 c^2 = -3√(25 a^6c^2)*√(5a)= -75a^3c√(5a)

-√320y^9 z^10=-√(64y^8z^10)*√(5y) = 8y^4z^5√(5y)

Answer 3

You need to show by using brackets, what the square root applies to. Is the first one:
sqrt(128) x^3
or sqrt(128x^3) ?