Question

please help. How would i convert f(x) = log (x) + 4 using the change of base formula?

Answer 1

Do they give any more background? convert f(x) to what?

Answer 2

i needs to graph it, but in order to put this function on geogebra i need to convert it

Answer 3

what base is it in now?

Answer 4

it worked?

Answer 5

yes

Answer 6

oh, thanks!

Answer 7

OK, grapher is a different program, but in geogebra
I found
lg(x) means log base 10

and ln(x) means log base e

Answer 8

I started geogebra
at the bottom I typed in
y= lg(x)+4
and then return. It plotted the curve

Answer 9

how will i know which to use? in or lg for diff problems?

Answer 10

I think if you see log(x) that generally means log base 10 so use lg(x) in geogebra
ln(x) means natural logarithm (log base e)

Answer 11

it is little L little n in ln (log natural )

Answer 12

how would i write this one? log0.2 (x + 6)

Answer 13

i typed this in, y=lg0.2(x+6) and it didnt work

Answer 14

Is that supposed to be log base 0.2 ?

Answer 15

whoops, yes, does that mean i type in?

Answer 16

y=in0.2(x+6) ?

Answer 17

you have to use
log_ugly_base(x) = lg(x)/lg( ugly_base)

Answer 18

so you want
y= lg(x+6)/lg(0.2)

Answer 19

replace
\[ \log_{0.2}(x) = \lg(x)/\lg(0.2) \]

Answer 20

Did you get it to work?

Answer 21

yes. you´re the beez kneez. thanks!

Answer 22

you could also use
y= ln(x+6)/ln(0.2)
it should give the same plot