Question

log8(x+1)-log8(x-4)=1.15 I solved the problem but I want to check if I did it correctly

Answer 1

what did you get for x?

Answer 2

I got x = -4

Answer 3

ln8(x+1)-ln8(x-4)
=ln8+ln(x+1)-ln8-ln(x-4)
=ln(x+1)-ln(x-4)
=ln[(x+1)/(x-4)]=1.15
(x+1)/(x-4)=10^1.15
(x+1)=14.13(x-4)
13.13x=5
x=5/13.13=0.38:)

Answer 4

@Egirl01 sry as if x=-4
8(x+1) become -ve and then log is not defined in that region and you have to take complex that doesn't work here:)

Answer 5

@Aperogalics i think by log8(x+1) he means log base 8

Answer 6

yeah, that was my fault. i meant log base 8

Answer 7

i should've done a better job displaying that, however, i still feel my answer is wrong

Answer 8

do you mind if I show you step by step how I got the answer?

Answer 9

Ohhhh all my work goes to waste:(

Answer 10

haha, i'm sorry!

Answer 11

ya show step by step i will not mind:)

Answer 12

i got x is approx 4.5

Answer 13

10.93*4+1=9.93x
x=4.5:)

Answer 14

http://www.wolframalpha.com/input/?i=log8(x%2B1)-log8(x-4)%3D1.15&t=crmtb01&f=rc

if youre never sure, ask wolfram alpha
wolframalpha.com

Answer 15

i believe on myself only:)

Answer 16

i corrected an error myself

Answer 17

but i got 4.09 instead of 4.5, i'll show you what i did

Answer 18

log base 8(x+1)/log base 8(x-4)
8^1.15 = x+1/x-4
(x-4)10.928 = x+1/x-4 (x-4)
10.928x – 43.713 = x+1
Subtract 10.928x from both sides
-43.713 = -10.928x +1
Subtract 1 from both sides
-44.713 = -10.928x
Divide -10.928 on both sides
X = 4.09(slightly changed, sorry, made a minor error that I fixed before. However, this answer still may be wrong)

Answer 19

@Egirl01 you have done it wrong:(

Answer 20

Subtract 1 from both sides
-44.713 = -10.928x------------------wrong
-44.713=-9.928x (as there is x already on right hand side so 1 is subtracted)
:)

Answer 21

that's what i thought when I saw how you got it. I made the correction and I got the same answer as you

Answer 22

thank you!

Answer 23

done gave medals and close the questions........lol