Question

Logarithms

Answer 1

I thought you were soo smart, that you would know them by now. LOL jk jk.

Answer 2

Lol. I'm not a calculator. I can get stuck too! :P
@OpenstudyUser

Answer 3

Try distributing.

Answer 4

\[ \Large 9^{2x} + 2(9^{x+1}) = 40 \]
Correction^

Answer 5

Just tell me the next and step after that please.

Answer 6

write 9^(x+1) as 9^x.9
then put y=9^x.
solve the quadratic

Answer 7

DANG!!! KILL ME!!!!
My teacher told me that. -_-

Thanks for recalling @hartnn

Answer 8

Just guessing, can't we do it like this?
\[9^{2x} + 2(9^x \times 9) = 40\]
Ans so on?

Answer 9

Next? @micahwood50

Answer 10

didn't i tell u to do just that?

Answer 11

Yes, but you said me to write 9^x = y
Got that.

But can't we solve it by another way?
Something like:
\[9^{2x} + 2(9^x)\times 18=40\]

Answer 12

nopes, i don't think so....no formula for log(a+b) or log (a-b)

Answer 13

I see. THanks man.

Answer 14

Did you missed a +sign in your first step?
@micahwood50

Answer 15

@OpenstudyUser kept on distributing. :D

Answer 16

I atleast tried -_-

Answer 17

Just do what hartnn told you to do.

Answer 18

I want to learn your method too! @micahwood50

Answer 19

My "method" is incorrect. I just though lnab = ln (a + b), but it's actually lna + lnb so forgot it.

Answer 20

Oh. No problem. Thanks for trying though. :)

Answer 21

I solved it @hartnn .
got:

x = 0.315

Answer 22

what roots of quadratic did u get?

Answer 23

2, -20

Answer 24

yup.
can't be -20
so 9^x=2
x=0.315
u are correct!

Answer 25

Yep. Thanks.