document.write( "Question 149596: What is the maximum value of the function f(x) = (3-x)(5x + 35)? \n" ); document.write( "
Algebra.Com's Answer #109736 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
First, we need to find the zeros. \r
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\n" ); document.write( "\n" ); document.write( "\"%283-x%29%285x+%2B+35%29=0\" Set the expression equal to zero.\r
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\n" ); document.write( "\n" ); document.write( "Now set each factor equal to zero:\r
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\n" ); document.write( "\n" ); document.write( "\"3-x=0\" or \"5x+%2B+35=0\" \r
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\n" ); document.write( "\n" ); document.write( "Now solve for x for each factor:\r
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\n" ); document.write( "\n" ); document.write( "\"x=3\" or \"x=-7\" \r
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\n" ); document.write( "\n" ); document.write( "So the zeros of \"%283-x%29%285x+%2B+35%29\" are \"x=3\" or \"x=-7\"\r
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\n" ); document.write( "\n" ); document.write( "Now average the zeros to get \"%283%2B%28-7%29%29%2F2=%28-4%29%2F%282%29=-2\"\r
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\n" ); document.write( "\n" ); document.write( "So the axis of symmetry (ie the x-coordinate of the vertex) is \"x=-2\"\r
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\n" ); document.write( "\n" ); document.write( "Now plug in \"x=-2\" to find the y coordinate of the vertex \r
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\n" ); document.write( "\n" ); document.write( "\"f%28x%29=%283-x%29%285x+%2B+35%29\" Start with the given function.\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-2%29=%283-%28-2%29%29%285%28-2%29+%2B+35%29\" Plug in \"x=-2\"\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-2%29=%283%2B2%29%285%28-2%29+%2B+35%29\" Rewrite \"3-%28-2%29\" as \"3%2B2\"\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-2%29=%283%2B2%29%28-10+%2B+35%29\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-2%29=%285%29%2825%29\" Add\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-2%29=125\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "So the y coordinate of the vertex is \"y=125\"\r
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\n" ); document.write( "\n" ); document.write( "This means that the vertex is at the point (-2,125). Since the vertex is either the highest or lowest point (in this case the highest), this means that that the maximum value of the function is \"125\"
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