SOLUTION: Solve to four decimal places: log(4) z+log(4)(z-3)=1. Thanks

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Question 43875: Solve to four decimal places: log(4) z+log(4)(z-3)=1.
Thanks
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
log(z) + log(z-3) = 1
log(z(z-3)) = 1
+z%28z-3%29+=+4%5E1+
z(z-3) = 4
+z%5E2+-+3z+=+4+
+z%5E2+-+3z+-+4+=+0+
(z-4)(z+1) = 0
so z-4=0 or z+1=0
z=4 or z=-1

z=-1 is not a valid answer since log(negative number) is not allowed.

So, answer is z=4

jon.