## Testing123guest one year ago plz help for medal @Michele_Laino

1. Testing123guest

2. Michele_Laino

If I call with N the missing exponent, we can write this: $\Large {\left( {{2^{ - 5}}} \right)^N} = {2^{ - 15}}$ and subsequently I apply the rule of power of power, so I get this condition: $\Large - 5 \cdot N = - 15$ what is N?

3. Testing123guest

-3?

4. Michele_Laino

I think no, since: -5 * -3= +15

5. Testing123guest

-5 * 3 = -15

6. Michele_Laino

correct! it is N=3

7. Testing123guest

thanks man u rock i will talk to u tomorrow i am going t hop off my computer

8. Michele_Laino

ok! :)

9. Testing123guest

wait i have one more question sorry

10. Michele_Laino

11. Testing123guest

12. Michele_Laino

We can rewrite your expression as below: $\Large \frac{{{7^{ - 3}} \cdot {7^9}}}{{{7^{ - 8}}}} = {7^{ - 3}} \cdot {7^9} \cdot {7^8}$ Now I apply the rule of multiplication of power with the same basis, so I get: $\Large \frac{{{7^{ - 3}} \cdot {7^9}}}{{{7^{ - 8}}}} = {7^{ - 3}} \cdot {7^9} \cdot {7^8} = {7^{ - 3 + 9 + 8}} = ...?$

13. Testing123guest

363?

14. Testing123guest

sorry my computer froze

15. Michele_Laino

what is -3+9+8=...?

16. Testing123guest

14

17. Michele_Laino

correct! so what is the right option?

18. Testing123guest

D?

19. Michele_Laino

option D is not $\Large {7^{14}}$

20. Michele_Laino

you have to search for $\Large {7^{14}}$

21. Testing123guest

positive 14 or negative 14

22. Michele_Laino

-3+9+8= +14 so?

23. Testing123guest

a

24. Michele_Laino

yes!

25. Testing123guest

u rock

26. Michele_Laino

thanks! :)