## Cutiepo0 3 years ago How to solve: log(x+2) + log(x-1) = 1

1. sauravshakya

Hint: loga + logb = log(a/b)

2. sauravshakya

Does it help?

3. Cutiepo0

Hmm give me a sec

4. Cutiepo0

Not really :\$ the answer is 3 and that just gives me a quadratic formula

5. Chlorophyll

Are they base 10?

6. Cutiepo0

yes

7. Cutiepo0

I assume

8. sauravshakya

1=log10

9. sauravshakya

So, log(x+2) + log(x-1) = 1 log{(x+2)(x-1)} = log10

10. sauravshakya

That may help

11. Chlorophyll

Do you know what to do when both 2 sides have the same base?

12. Cutiepo0

I don't think so (chlorophyll)

13. Chlorophyll

So learn the rule, both logs will be CANCELLED out :)

14. Cutiepo0

really? okay, but then I'm still confused :\$

15. Cutiepo0

okay, so it would still be (x+2)(x-1) = 10

16. Cutiepo0

x^2 +x -2 = 10

17. Cutiepo0

or x^2+x-12 actually

18. Cutiepo0

=0

19. Cutiepo0

20. Cutiepo0

and then is the positive root just my answer?

21. Chlorophyll

Perfect! I'm waiting for your x = ...?

22. Cutiepo0

3

23. Chlorophyll

Wow, why's so fast! Hmm...

24. Chlorophyll

Anyway, correct!

25. Chlorophyll

Questions?

26. Cutiepo0

um no thanks :) will try that with the next question now!