Given the parent functions f(x) = log10 x and g(x) = 5x − 2, what is f(x) • g(x)?
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OpenStudy (anonymous):
@Astrophysics
OpenStudy (astrophysics):
\[f(x)g(x) = \log_{10}x (5x-2)\]
OpenStudy (astrophysics):
You're just multiplying the functions
OpenStudy (anonymous):
Thanks! Can I ask one more?
OpenStudy (anonymous):
If f(x) = log2 (x + 4), what is f−1(3)?
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OpenStudy (astrophysics):
The \[f^{-1}\] represents inverse
OpenStudy (anonymous):
yes:)
OpenStudy (astrophysics):
To find the inverse:
Replace f(x) with y
Switch x's and y's, so put x where y is and x where y is.
Solve for y
Replace y with f^-1(x)
OpenStudy (astrophysics):
Once you find the inverse just plug in 3 into the function and evaluate :-)
OpenStudy (anonymous):
y=log2(x+4)
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OpenStudy (astrophysics):
good keep going
OpenStudy (anonymous):
x=log2(y+4)
OpenStudy (astrophysics):
right
OpenStudy (anonymous):
im confused on how to solve for "Y"
OpenStudy (astrophysics):
Since it's \[\log_2\] as the base we will have to take the power of 2 to on both sides so the following \[\huge 2^x = 2^{\log_2(y+4)} \implies 2^x = y+4\]
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OpenStudy (anonymous):
hmm then wouldnt we have to get y alone?
OpenStudy (anonymous):
Would the answer be 8?
OpenStudy (loser66):
f(a) =b , hence \(f^{-1} (b) =a\) ok?
OpenStudy (loser66):
we need find \(f^{-1} (3) \) of \(f(x) = log 2(x+4)\), right?
That is just let log 2(x+4) =3, and solve for x.
OpenStudy (astrophysics):
You can do either way you should get same result
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OpenStudy (anonymous):
2?
OpenStudy (astrophysics):
No, \[y=2^x-4 \implies f^{-1}(x) = 2^x-4 \implies f^{-1}(3) = 2^3-4\]
OpenStudy (anonymous):
oh! okay so then I got, 4
OpenStudy (loser66):
confirm: \(log (2(x+4))\) or (x+4)*log 2??
OpenStudy (astrophysics):
Yes, 4 sounds betters :)
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OpenStudy (anonymous):
2x2x2=4x2=8
8-4=4
:)
OpenStudy (astrophysics):
I think the original question was \[\log_2(x+4)\] right?
OpenStudy (anonymous):
yes
OpenStudy (astrophysics):
Ok we're good then
OpenStudy (astrophysics):
Thanks @Loser66
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