Mathematics
11 Online
OpenStudy (anonymous):
log_6(x)+log_6(x+1)=1
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OpenStudy (unklerhaukus):
Combine the logs on the left like this
\[\log_b(N)+\log_b(M)=\log_b(N\times M)\]
OpenStudy (anonymous):
Yeah I got log_6(x)(x+1)=1 so far
OpenStudy (unklerhaukus):
Now use the definition of a log
\[\log_bz=y\quad\iff\quad z=b^y\]
OpenStudy (unklerhaukus):
can you do this part?
OpenStudy (kc_kennylau):
That means do the 6 to the power both sides
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OpenStudy (unklerhaukus):
yes,
OpenStudy (kc_kennylau):
@MikeB55 your turn now :)
OpenStudy (shamim):
log_6(x^2+x)=log_6 6 @MikeB55
OpenStudy (unklerhaukus):
you'll get a quadratic which has two solutions,
only one of these solutions solves the original equation
OpenStudy (kc_kennylau):
Looks like Mike's not here, let's wait for his return :)
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OpenStudy (anonymous):
Hey sorry everyone
OpenStudy (anonymous):
I'm at x^2+x=6
OpenStudy (anonymous):
So x=2
OpenStudy (kc_kennylau):
Yep
OpenStudy (anonymous):
Thanks everyone
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OpenStudy (kc_kennylau):
no problem
OpenStudy (unklerhaukus):
that's right!, did you also get the number that solves the quadratic but not the log equation?
do you know why this solution doesn't work?
OpenStudy (kc_kennylau):
I assume he already knows it :)
OpenStudy (anonymous):
Yeah I got it!
OpenStudy (shamim):
why -3 is not accepted @Unkle
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OpenStudy (kc_kennylau):
Because log of negative is undefined
OpenStudy (anonymous):
Negative numbers can't be used to solve a log equation
OpenStudy (shamim):
ok
OpenStudy (unklerhaukus):
exactly