Final answer:
The expression (z^7 z^{-5})^{-2} simplifies to 1/z^4 by applying the laws of exponents to combine and subsequently simplify the terms.
Step-by-step explanation:
To simplify the expression (z^7 z^{-5})^{-2}, we first combine the exponents of the same base by adding them. Since we're multiplying z to different powers, according to the laws of exponents, we can add the exponents:
z^7 × z^{-5} = z^{7 + (-5)}
= z^2
Now, we raise this to the power of -2:
(z^2)^{-2} = z^{2 × (-2)}
= z^{-4}
And as a final step, because negative exponents indicate the reciprocal, we can write this as:
z^{-4} = 1/z^4
So, (z^7 z^{-5})^{-2} simplifies to 1/z^4.