1. What is the simplified for of 3a^4b^-2c^3
a)81a^4c^3/b^2
b) 81a^4/b^2c^3
c)3a^4/b^2c^3
d) 3a^4c^3/b^2
7. What is -a^-2 if a = -5?
a)-25
b)25
c) - 1/25
d) 1/25
9. What is the simplified for of -(14x)^0y^-7z
11. What is (-m)^-3 if m=2 and n =-24
13. Which of the following simplifies to a negitive number?
a) -4^-4
b) (-4)^-4
c)4^-4
d)1/4^-4
I just took a test on exponents and these questions stumped me!
Can someone explain them carefully?

Question

1. What is the simplified for of 3a^4b^-2c^3
a)81a^4c^3/b^2
b) 81a^4/b^2c^3
c)3a^4/b^2c^3
d) 3a^4c^3/b^2
7. What is -a^-2 if a = -5?
a)-25
b)25
c) - 1/25
d) 1/25
9. What is the simplified for of -(14x)^0y^-7z
11.  What is (-m)^-3 if m=2 and  n =-24
13. Which of the following simplifies to a negitive number?
a) -4^-4
b) (-4)^-4
c)4^-4
d)1/4^-4
I just took a test on exponents and these questions stumped me!
Can someone explain them carefully?