a ^ 3b ^ -2 / ab ^ -4, a ≠ 0, b ≠ 0
First we rewrite the expression respecting the properties of the exponents.
b ^ -2 = 1 / b ^ 2
1 / b ^ -4 = b ^ 4
We have then:
a ^ 3b ^ -2 / ab ^ -4
a ^ 3b ^ 4 / ab ^ 2
answer:
An expression using positive exponents is
D a^3b^4/ab^2