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# 3^(x+1)=4^(x-1) Solve for X

+107
1
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3^(x+1)=4^(x-1)

Solve for x! Can't for the life of me figure this out! I assume you have to use Logs!
Jan 25, 2012

#1
+3144
+48
3^(x+1)=4^(x-1) | *4

4*3^(x+1)=4^x

4*3^(x+1)=4^x | ln( .. ) on both sides, let's assume x will be larger 0

ln( 4*3^(x+1) ) = ln( 4^x )

x*ln(3)+ln(12) = x*ln(4) | -x*ln(4) and -ln(12)

x*ln(3)-x*ln(4)=-ln(12)

x*(ln(3)-ln(4))=-ln(12)

x=-ln(12)/(ln(3)-ln(4))

x ≈ 8.63768335861279
Jan 25, 2012

#1
+3144
+48

4*3^(x+1)=4^x

4*3^(x+1)=4^x | ln( .. ) on both sides, let's assume x will be larger 0

ln( 4*3^(x+1) ) = ln( 4^x )

x*ln(3)+ln(12) = x*ln(4) | -x*ln(4) and -ln(12)

x*ln(3)-x*ln(4)=-ln(12)

x*(ln(3)-ln(4))=-ln(12)

x=-ln(12)/(ln(3)-ln(4))

x ≈ 8.63768335861279
#2
+18
x=8,637
Jan 25, 2012
#8
+425
+15

They use a comma for a decimal point.

To avoid confusion, for a thousand, no need for a separator, use a space to separate.

1 234 = 1 thousand 2 hundreds 3 tens 4 ones

1,234 or 1.234 = 1 one 2 tenths 3 hundredths 4 thousandths

MWizard2k04  Apr 7, 2016
#3
+13

no, 8.637.

Oct 26, 2014
#5
+24

Woah, this is the first question ever asked!

Jan 21, 2016
#6
+5265
+19

And here we have the first question ever asked. It was asked on Jan. 25, 2012. Wonderful question.

Mar 11, 2016
#9
+9665
+27

The first question ever asked :O

It was hard

Apr 16, 2016
#10
+1886
+16

Aug 20, 2016
#11
+17

YEEEEEEEEEEEEEEEEEEE!!!!! First question. Noice

Oct 14, 2016
#12
+180
+13

YOING First question nice

Dec 19, 2016
#13
+501
+9

Look what a hard first question!!!

Davis  Mar 3, 2017