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Mathematics 7 Online
OpenStudy (anonymous):

Help!?! Use the functions to answer the question.

OpenStudy (helder_edwin):

use the definition \[ (f\circ g)(4)=f(g(4)) \] first g(4)=?

OpenStudy (anonymous):

I think that's the answer.. am I right?

OpenStudy (helder_edwin):

no. since g(x)=x+3 then g(4) means you replace the "x" by 4 so \[ g(4)=4+3=7 \]

OpenStudy (helder_edwin):

got it?

OpenStudy (anonymous):

ohhhh

OpenStudy (helder_edwin):

now u know that g(4)=7. so \[ (f\circ g)(4)=f(g(4))=f(7)= \] so f(7)=?

OpenStudy (anonymous):

14?

OpenStudy (anonymous):

how do I find it?

OpenStudy (helder_edwin):

do the same. \(f(x)=4x-7\) so \[ f(7)= \]

OpenStudy (anonymous):

subtract both sides?

OpenStudy (helder_edwin):

for instance \[ f(5)=4\cdot5-7=20-7=13 \]

OpenStudy (anonymous):

oh wait but that's not a choice

OpenStudy (anonymous):

I'm confused :/

OpenStudy (helder_edwin):

do it. it's easy f(7)=?

OpenStudy (helder_edwin):

i gave u an example. with 5 instead of 7. you do it with 7

OpenStudy (helder_edwin):

\[ f(\color{red}{5})=4\cdot\color{red}{5}-7=20-7=13 \]

OpenStudy (anonymous):

so what do I do with 13?

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