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anewbie
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Find the inverse of the function f(x)=x^{2}8x+4, where <4. State its domain.
 one year ago
 one year ago
anewbie Group Title
Find the inverse of the function f(x)=x^{2}8x+4, where <4. State its domain.
 one year ago
 one year ago

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anewbie Group TitleBest ResponseYou've already chosen the best response.0
\[where x \le 4\]
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
can you complete the square ? know how to ?
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
\(f(x)=x^28x+4= (x...)^2...\)
 one year ago

anewbie Group TitleBest ResponseYou've already chosen the best response.0
so the answer is inversef(x)=4+sqrt{x+12} . domain is x bigger or equal 12 ?
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
to be more precise, \(f^{1}(x)=4\pm \sqrt{x+12} \) the domain \(x \ge 12 \) is correct.
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
wait, its given that x<4
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
so, it'll be only \(f^{1}(x)=4  \sqrt{x+12}\) with same domain.
 one year ago

anewbie Group TitleBest ResponseYou've already chosen the best response.0
how can we understand that it is minus when x<4 ?
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
4+ anything means >4 4 anything means <4
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
does that clear it up ? or you have different doubt altogether ? :P
 one year ago

anewbie Group TitleBest ResponseYou've already chosen the best response.0
a little bit :D because it tells about x but we take the function <4 :/
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
oh, .... domain of f(x) means range of its inverse function \(f^{1}(x)\) here, x<4 is domain of f(x), so range of \(f^{1}(x)\) is x<4 , means \(f^{1}(x)\) has least value of 4, so we discard 4+sqrt {x+12} because that will be >4
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
***range of \(f^{1}(x)\) is \(f^{1}(x)\)<4
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
***maximum value of 4
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
sorry for the typos.
 one year ago

anewbie Group TitleBest ResponseYou've already chosen the best response.0
oh. okey. thank youu :)
 one year ago

hartnn Group TitleBest ResponseYou've already chosen the best response.1
welcome ^_^
 one year ago
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