Ask your own question, for FREE!
Mathematics 18 Online
OpenStudy (anonymous):

Intermediate Algebra question in comments, Please help :)

OpenStudy (anonymous):

\[64^{3x}=16^{x+1}\]

OpenStudy (anonymous):

Hint: Try to make the base a common number ,Can you guess what is it ?

OpenStudy (anonymous):

4

OpenStudy (anonymous):

iv'e gotten to \[(3x)\log64=(x+1)\log16 \] using the method i was taught.

OpenStudy (anonymous):

im not sure what to do after this though

OpenStudy (anonymous):

i have to provide the value of x and an estimate to the fourth decimal place

OpenStudy (anonymous):

Great So by making the base similar , we will get : \[\Large 4^{3(3x)} = 4^{2(x+1)} \] Since the base = base ,therefore the power = power . 3(3x)=2(x+1) 9x=2x+1 7x=1 x=1/7

OpenStudy (anonymous):

okay i see

OpenStudy (anonymous):

k, thx

OpenStudy (anonymous):

Back :3

OpenStudy (anonymous):

:D

OpenStudy (anonymous):

\[\Large (3x)\log64=(x+1)\log16\] Combine similar terms , \[\Large \frac{(3x)}{(x+1)}=\frac{\log16}{\log64}\] Here is a hint that i always do to prevent confusing , Let Log16/Log64 = m therefore 3x/x+1=m then \[\large xm+m=3x\] Now combine again the x \[\Large xm-3x=m\] Take the x common , \[\Large x(m-3)=m\] Then \[\Large \color{Red} X=\frac{m}{m-3}\]

OpenStudy (anonymous):

Now Substitute The value of m and get X :) P.S:Letting Log16/Log64 = m ,Is not necessary ..I did it only to abbreviate it

OpenStudy (anonymous):

You got what i said xD ?

OpenStudy (anonymous):

sry, i was away for a sec. im not quite sure i understood what u mean by m

OpenStudy (anonymous):

Ignore that part ,Just do the Multiply them by each other .

OpenStudy (anonymous):

multiply what by what?

OpenStudy (anonymous):

sry im slow

OpenStudy (anonymous):

lol

OpenStudy (anonymous):

(log16/log64)(x+1)=3x

OpenStudy (anonymous):

That ^

OpenStudy (anonymous):

i see

OpenStudy (anonymous):

so what do i do after that?

OpenStudy (anonymous):

combine the x together

OpenStudy (anonymous):

and take x common Then Calulate it

OpenStudy (anonymous):

calculate

OpenStudy (anonymous):

\[\large 64^{3x}=16^{x+1}\] \[\large (4)^{3(3x)}=4^{2(x+1)}\] \[\large 9x=2x+2\] \[\large 7x=2\] \[\large x=\frac{2}{7}\]

OpenStudy (anonymous):

I already did that !

OpenStudy (anonymous):

?, two different answers though.

OpenStudy (anonymous):

Why would you use logs when you can just do that.

OpenStudy (anonymous):

x=1/7

OpenStudy (anonymous):

He is right ,i missed the 2 7x=2

OpenStudy (anonymous):

That's wrong. YOu didn't expand/distribute properly.

OpenStudy (anonymous):

i need it in the format of log(a)/log(b) i think

OpenStudy (anonymous):

*sigh

OpenStudy (mertsj):

\[64^{3x}=16^{x+1}\]

OpenStudy (mertsj):

\[(4^{3})^{3x}=(4^{2})^{x+1}\]

OpenStudy (anonymous):

Then \[x=\frac{2}{7}\] \[\log x=\log \frac{2}{7}\] \[\frac{\log x}{\log \frac{2}{7}}=1\]

OpenStudy (mertsj):

\[4^{9x}=4^{2x+2}\]

OpenStudy (mertsj):

\[9x=2x+2\] 7x=2 x=2/7

OpenStudy (anonymous):

\[\log x=\log \frac{2}{7}\] \[\log x=\log 2 -\log 7\] I don't know why you need it in that form and you can't get it into that form if you want x as the subject.

OpenStudy (anonymous):

@sgta101

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!