+0

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

+91
5809
13
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
+40
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
+40

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
#8
+12

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
#5
+21

Woah, this is the first question ever asked!

Jan 21, 2016
#6
+15

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

Mar 11, 2016
#9
+21

The first question ever asked :O

It was hard

Apr 16, 2016
#10
+14

Aug 20, 2016
#11
+13

YEEEEEEEEEEEEEEEEEEE!!!!! First question. Noice

Oct 14, 2016
#12
+9

YOING First question nice

Dec 19, 2016
#13
+5

Look what a hard first question!!!

Davis  Mar 3, 2017