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C2 confusion (logarithms)

Hi, I have the question "Solve:

log2(x+1)−log2x=log27log_2 (x+1) - log_2 x = log_2 7"

Which I have in the form:

log2(x+1x)=log27log_2 ( \frac{x+1}{x} ) = log_2 7

x+1x=7\frac {x+1}{x} = 7

but have no idea what to do to solve for xx :redface:. This is probably something silly, so forgive my ignorance if so, but it's really annoying me right now...
x/x = 1?
Reply 2
Avatar for Goldfishy
Goldfishy
8
Original post by The Muffin Man_
x+1x=7\frac {x+1}{x} = 7


Multiply through by x.
Reply 3
Avatar for JoMo1
JoMo1
12
multiply through by x.
Reply 4
Avatar for Gemini92
Gemini92
Original post by The Muffin Man_
Hi, I have the question "Solve:

log2(x+1)−log2x=log27log_2 (x+1) - log_2 x = log_2 7"

Which I have in the form:

log2(x+1x)=log27log_2 ( \frac{x+1}{x} ) = log_2 7

x+1x=7\frac {x+1}{x} = 7

but have no idea what to do to solve for xx :redface:. This is probably something silly, so forgive my ignorance if so, but it's really annoying me right now...


Multiply through by x to get x+1=7x and work from there.
Original post by The Muffin Man_
Hi, I have the question "Solve:

log2(x+1)−log2x=log27log_2 (x+1) - log_2 x = log_2 7"

Which I have in the form:

log2(x+1x)=log27log_2 ( \frac{x+1}{x} ) = log_2 7

x+1x=7\frac {x+1}{x} = 7

but have no idea what to do to solve for xx :redface:. This is probably something silly, so forgive my ignorance if so, but it's really annoying me right now...


x + 1 = 7x

6x = 1

x = 16\frac {1}{6}
(edited 13 years ago)
Original post by thegodofgod
x + 1 = 7x

6x = 1

x = 16\frac {1}{6}


Ah, thank you. :colondollar:
Reply 7
Avatar for Sasukekun
Sasukekun
7
In case you didn't get it after the fifth time. You multiply through by x.
Original post by The Muffin Man_
Ah, thank you. :colondollar:


No problems :smile:

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