Question

Hey guys, I need help with logarithms.

Answer 1

Could you help with the circled questions?

Answer 2

Nice, but I don't have a microscope on me.

Answer 3

Oh man so small, lol

Answer 4

drat.. it's tiny... omg I know why.. gimme a sec

Answer 5

It's not letting me attach the big one... :/

Answer 6

You mean the upload takes long time?

Answer 7

http://tinypic.com/r/2u8gvpl/5

Answer 8

see if that works

Answer 9

Which one?

Answer 10

11.)
\[\ln(4.5^{x})=\ln78\]
\[xln(4.5)=78\]
\[x=\frac{\ln78}{\ln4.5}\]

Answer 11

12)
\[x=(0.592)^{\frac{2}{3}}\]

Answer 12

You already have two people helping you, so I'll just write out the identities.

ln(x)=y→e^y=x
ln(x^n)=nln(x)
ln(xy)=ln(x)+ln(y)
ln(x/y)=ln(x)-ln(y)

Answer 13

15)
log^2(4x+10)-log^2(x+1)=3

log^2(2(2x+5))-log^2(x+1)=3

log^2((2(2x+5))/(x+1))=3

2^(log^2((2(2x+5))/(x+1)))=2^(3)

(2(2x+5))/(x+1)=8

(2(2x+5))/(8)=(x+1)

(2x+5)/(4)=(x+1)

(2x+5)/4=x+1

Least common denominator: 4

2x+5=4x+4

-2x+5=4

-2x=-1

x=1/2

Answer 14

The circled ones.. I'm horrible with logs, our teacher sucks at teaching :/

Answer 15

I am solving 19
\[\log_4 \frac{x^2 + 3x}{x+5} = log_4 4\]
\[x^2 + 3x = 4x + 20\]
\[x^2 - x -20=0\]
\[(x+4)(x-5)=0\]
\[x=-4,5\]

Answer 16

what's 17?

Answer 17

17)
log^2(x+5)-log^2(x-2)=3

log^2((x+5)/(x-2))=3

2^(log^2((x+5)/(x-2)))=2^(3)

(x+5)/(x-2)=8

(x+5)/(8)=(x-2)

(x+5)/(8)=x-2

Least common denominator: 8

x+5=8x-16

-7x+5=-16

-7x=-21

x=3

Answer 18

@Sam for number 11.. where in the ln come from? I though that was for natural logs only.. :/

Answer 19

same thing, replace ln( with log( :)

Answer 20

:) thank you soo much!!!

Answer 21

no problem :)