document.write( "Question 113796: Given f(x)=x^3+2 and g(x)=cube_root(x-2), show that f(g(x))=x and g(f(x))=x. Graph both functions on the same set of coordinate axes.
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Algebra.Com's Answer #82813 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
#3\r
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\n" ); document.write( "\n" ); document.write( "\"f%28x%29=x%5E3%2B2\" Start with f(x)\r
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\n" ); document.write( "\n" ); document.write( "\"f%28g%28x%29%29=%28g%28x%29%29%5E3%2B2\" Plug in \"x=g%28x%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"f%28g%28x%29%29=%28root%283%2Cx-2%29%29%5E3%2B2\" Replace each \"g%28x%29\" with \"root%283%2Cx-2%29\". This is given since \"g%28x%29=root%283%2Cx-2%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"f%28g%28x%29%29=%28x-2%29%2B2\" Cube the cube root (these two functions \"undo\" each other and cancel out)\r
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\n" ); document.write( "\n" ); document.write( "\"f%28g%28x%29%29=x\" Combine like terms\r
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\n" ); document.write( "\n" ); document.write( "So this shows that \"f%28g%28x%29%29=x\" \r
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\n" ); document.write( "\n" ); document.write( "\"g%28x%29=root%283%2Cx-2%29\" Start with g(x)\r
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\n" ); document.write( "\n" ); document.write( "\"g%28f%28x%29%29=root%283%2Cf%28x%29-2%29\" Plug in \"x=f%28x%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"g%28f%28x%29%29=root%283%2Cx%5E3%2B2-2%29\" Replace f(x) with \"x%5E3%2B2\"\r
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\n" ); document.write( "\n" ); document.write( "\"g%28f%28x%29%29=root%283%2Cx%5E3%29\" Combine like terms\r
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\n" ); document.write( "\n" ); document.write( "\"g%28f%28x%29%29=x\" Take the cube root of \"x%5E3\" to get x. Remember the cube root and the cube cancel each other out.\r
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\n" ); document.write( "\n" ); document.write( "So this shows that \"g%28f%28x%29%29=x\" \r
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\n" ); document.write( "\n" ); document.write( "Now if we graph the two functions, we get\r
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