What is each product or quotient in simplest form?

a) √3(4√3)
b)√x^3/3√x^2
c)√7(3√7)

√3(4√3) = 4√3√3 = 4(3) = 12

hard to interpret without parentheses...
√x^3/(3√x^2) = √(x^3/3x^2) = √(x/3) = √(3x) / 3

√7(3√7) = 3√7√7 = 3*7 = 21