I need all of these answers with work shown and/or explained, please help..

1. -(5)^-1

-1/5

3. -1/y^-4

-y^4

4. 5 ^ 4 x 5^7

5^11

7. (5t ^ 3)^-4

1/625t^12

12. What is the order of 4 x 10^-7, 7 x 10^-9, 1 x 10^4, 2 x 10^4

7 x 10^-9, 4 x 10^-7, 1 x 10^4, 2 x 10^4

13. Find the simplified form of the expression. Give your answer in scientific notation
(8 x 10^4)(9 x 10^-8)

7.2 x 10^-3

14. Astronomers measure long distances in light-years. One light year is the distance that light can travel in one year, or approcimately 5.88 x 10^12 miles. Suppose a star is 9.8 x 10^1 light-years from Earth. in scienctific notation, approximately how many miles is it?

5.76 x 10^14 miles

15. A dinosaur fossil is 91,910,000 years old. How canyou express this age in scientific notation with the highest level of precision?

9.191x10^7

16. Radio signals travel at a rate of 3 x 10^8 meters per second. How many seconds would it take for a radio signal to travel from a satellite to the surface of Earth if the satellite is orbiting at a height of 3.6 x 10^7 meters? (Hint: Time is distance divided by rate.)

1.2 x 10^-1

18. Does the rule y=6x^7 represent an exponential function?

no