Final answer:
The multiplication of the given expressions results in a single term with a numerator of -63y and a denominator of x^3.
Step-by-step explanation:
When multiplying expressions with exponents, you multiply the coefficients and add the exponents of like bases. In the given expression (7x^{-7}y^{-4})*(-9x^4y^5), apply these rules. First, multiply the coefficients 7 and -9 which gives -63. Then, for the variable x, add the exponents -7 and 4 together (-7 + 4) to get -3. For the variable y, add the exponents -4 and 5 together (-4 + 5) to get 1. So, the expression simplifies to -63x^{-3}y.
Because of the negative exponent on x, the term x^{-3} is the same as 1/x^3, indicating that it belongs in the denominator. The final expression with the numerator and denominator separated would be:
Numerator: -63y
Denominator: x^3
Remember that any term with a negative exponent moves to the opposite part of the fraction to become positive. In this case, x^-3 moves from the numerator to the denominator.