can someone help me with solving exponential equations with unequal bases?

Question

anonymous · Answer

Solve 4x = 12
my answer choices are 
 x ≈ 0.27

 x ≈ 0.56

 x ≈ 1.79

 x ≈ 19.93
but i keep getting the answer is 3??? can someone help me?

loser66 · Answer

hh,mmmmm!! 4^x or 4x???

loser66 · Answer

from your options I guess it is $$4^x= 12 ---> \log_{4}12 =x= 1.79 $$

phi · Answer

$$ 4^x =12 $$
take the log of both sides.  You can use log of any base, but your calculator has log (base 10)  and ln (natural log  i.e. log base e)

if we use log base 10:
$$ \log(4^x) = \log(12) $$

use the rule
$$ \log(a^b)= b\ \log(a) $$
to write the problem as
$$ x\log(4) = \log(12) $$
remember that log(4) is just some number.  Divide both sides by log(4)
$$ x= \frac{\log(12)}{\log{4}} $$

you will need a calculator to get a decimal number....

loser66 · Answer

@phi can you go here, http://openstudy.com/study#/updates/516d4a69e4b063fcbbbcd67c