Math help
posted by Shawn on .
Where appropriate, include the approximation to the nearest tenthousandth.
31.) log(x4)+ log(x+4)= log4
I have the answer as 4
Is this answer right?

log a + log b is same as log ab
so log(x^24)=log4
taking antilogs
x^24=4 solve for 4
check my thinking. 
Okay x^24 = 4
x^2= 8
sqrt(x^2)= sqrt 8
x= 2.83 is this right? 
log k has a nasty habit of becoming undefined if k is not positive.
you answer of x = 2.832 is correct according to the steps taken, but...
when we sub into log (x4) we get log (1.168 which is undefined,
so there is no solution in the set of real numbers for your equation 
Going back and looking over the previous solutions, I noticed that the original nonlog equation should have said:
x^216 = 4
so x^2 = 20
x = √20 = 4.472136
which works upon substituting.