Mathematics
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OpenStudy (anonymous):
Help? logs.
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OpenStudy (anonymous):
what logs?
OpenStudy (anonymous):
yea what logs
OpenStudy (anonymous):
http://web2.0calc.com/
Rose for then your doing logarithmic form try useing that calc
OpenStudy (anonymous):
logarithmic form Is a other type of math equations
OpenStudy (anonymous):
or logs
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OpenStudy (anonymous):
\[\log_{9}(-11x+2)=\log_{9}(x^{2}+30)\]
Do I divide by \[\log_{9} \] on both sides?
I need to find x
OpenStudy (anonymous):
no you don't divide
OpenStudy (anonymous):
you subtract
OpenStudy (anonymous):
No I divide because it's opposite of multiplying.
OpenStudy (anonymous):
1- log(A-B)=logA/logB
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OpenStudy (anonymous):
yes you got it
OpenStudy (anonymous):
In Logs, we don't say like that..
OpenStudy (anonymous):
2- bring log x in one side
OpenStudy (anonymous):
we say, "take the antilogarithm" on both sides..
OpenStudy (anonymous):
It is simple, don't make it hard..
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OpenStudy (anonymous):
@AJ01 you're not making sense
@waterineyes then how do I do it?
OpenStudy (anonymous):
you have log base 9, on both the sides, so take antilog:
\[If \quad \ln_a(x) = \ln_a(y), \ \ then \ \ x = y\]
OpenStudy (anonymous):
So:
\(\log_9(-11x+2) = \log_9(x^2 +30)\)
\(\implies -11x + 2 = x^2 + 30\)
OpenStudy (anonymous):
Now, this is just a quadratic equation, find \(x\)..
OpenStudy (anonymous):
@AJ01 Also this is correct formula:
\[\log(a) - \log(b) = \log(\frac{a}{b})\]
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OpenStudy (anonymous):
So I use the quadratic equation
\[x=\frac{ -b \pm \sqrt{b^{2}-4ac} }{ 2a }\]
\[x^{2}+11x+28\]
OpenStudy (anonymous):
\[x=\frac{ -11 \pm \sqrt{11^{2}-4*1*28} }{ 2*1 }\]
OpenStudy (anonymous):
you can also use Factorization Method if you want.. 7 and 4 are the factors..
OpenStudy (anonymous):
\[x^2 + 11x + 28 = 0 \\ (x+7)(x+4) = 0 \\ x = -7 \quad or \ \quad x = -4\]
OpenStudy (anonymous):
Getting??
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OpenStudy (anonymous):
Oh right! I always forget about factoring.
OpenStudy (anonymous):
Good..
OpenStudy (anonymous):
Could you help me with another. It's a little different.
OpenStudy (anonymous):
Sure..