Answer:
c
Explanation:
Keep in mind, whatever is inside of the square root, stays inside of the square root, and whatever is outside, stays outside, they don't multiply together. With parenthesis, exponents multiply, if there's no parenthesis, the exponents don't multiply. In this case, the exponents add.
Multiply each one together:
sqrt(6x^2) x sqrt(9x) = sqrt(54x^3)
sqrt(6x^2) x -(x sqrt(5x^5)) = -x sqrt(30x^7)
4 sqrt(8x^3) x sqrt(9x) = 4 sqrt(72x^4)
4 sqrt(8x^3) x -(x sqrt(5x^5)) = -4x sqrt(40x^8)
Then simplify:
sqrt(54x^2) = 3x sqrt(6x)
x sqrt(30x^7) = -x^4 sqrt(30x)
4 sqrt(72x^4) = 24x^2 sqrt(2)
-4x sqrt(40x^8) = -8x^5 sqrt(10)