SOLUTION: solve for x Log3x+log3(x-4)=1 hint: all 3 are subscripts (I don't know how to put subscript here please tell me all i know is writing superscript like this symbol(^).what

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: solve for x Log3x+log3(x-4)=1 hint: all 3 are subscripts (I don't know how to put subscript here please tell me all i know is writing superscript like this symbol(^).what      Log On


   

Question 684805: solve for x
Log3x+log3(x-4)=1
hint: all 3 are subscripts
(I don't know how to put subscript here please tell me all i know is writing superscript like this symbol(^).whats for subscript?
Found 2 solutions by Alan3354, josmiceli:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
solve for x
Log3x+log3(x-4)=1
----------------
log%283%2Cx%29+%2B+log%283%2C%28x-4%29%29=1
log%283%2C3%28x-4%29%29=1
3(x-4) = 3
x = 5
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Click the Show source to see how it's entered.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The format for subscript looks like
log( 3,x ), and when you put it in the
"%22+and+%22" symbols you get
+log%283%2Cx%29+
------------
+log%28+3%2Cx+%29+%2B+log%28+3%2C%28+x-4+%29%29+=+1+
The trick here is to say +1+=+log%28+3%2C3+%29+
+log%28+3%2Cx+%29+%2B+log%28+3%2C%28+x-4+%29%29+=+log%28+3%2C3+%29+
+log%28+3%2Cx%2A%28x-4%29+%29+=+log%28+3%2C3+%29+
+x%2A%28+x-4+%29+=+3+
+x%5E2+-+4x++-+3+=+0+
use the quadratic formula
+x+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+
+a+=+1+
+b+=+-4+
+c+=+-3+
+x+=+%28-%28-4%29+%2B-+sqrt%28+%28-4%29%5E2+-+4%2A1%2A%28-3%29+%29%29+%2F+%282%2A1%29+
+x+=+%28+4+%2B-+sqrt%28+16++%2B+12+%29%29+%2F+2+
+x+=+%28+4+%2B-+sqrt%28+28+%29%29+%2F+2+
+x+=+%28+4+%2B+5.2915+%29+%2F+2+
+x+=+9.2915+%2F+2+
+x+=+4.64575+
check answer:
+x%5E2+-+4x++-+3+=+0+
+4.64575%5E2+-+4%2A4.64575++-+3+=+0+
+21.583+-+18.59+-+3+=+0+
+21.583+-+21.59+=+0+
close enough
You can also go back and use the negative
square root of 28 and get another answer