document.write( "Question 1000359: Plz help me to explain the range of this equation. {f(x)=1÷x^2-2x-3} \n" ); document.write( "
Algebra.Com's Answer #617844 by Theo(13342)\"\" \"About 
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the denominator of that equation is x^2 - 2x - 3.\r
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\n" ); document.write( "\n" ); document.write( "we'll call that g(x).\r
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\n" ); document.write( "\n" ); document.write( "g(x) is a quadratic equation that can be solved to provide the following information:\r
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\n" ); document.write( "\n" ); document.write( "the graph crosses the x-axis at x = -3 and x = 1.
\n" ); document.write( "the minimum point on the graph is at (1,-4)
\n" ); document.write( "the graph is positive from x > - infinity to x < -3.
\n" ); document.write( "the graph is negative between x > -3 to x < 1.
\n" ); document.write( "the graph goes positive again between x > 1 to x < infinity.\r
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\n" ); document.write( "\n" ); document.write( "the range of g(x) is all values of y greater than or equal to -4.\r
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\n" ); document.write( "\n" ); document.write( "f(x) is equal to 1 / g(x).\r
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\n" ); document.write( "\n" ); document.write( "f(x) is therefore the reciprocal of g(x).\r
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\n" ); document.write( "\n" ); document.write( "when g(x) is going towards positive infinity, f(x) is going towards 0 from the positive side.
\n" ); document.write( "when g(x) is going towards negative infinity, f(x) is going towards 0 from the negative side.
\n" ); document.write( "when g(x) is going towards 0 from the positive side, f(x) is going towards positive infinity.
\n" ); document.write( "when g(x) is going towards 0 from the negative side, f(x) is going towards negative infinity.\r
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\n" ); document.write( "\n" ); document.write( "every value of f(x) is going to be equal to 1 divided by every value of g(x).\r
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\n" ); document.write( "\n" ); document.write( "when g(x) is at -4, f(x) will be at -.25.\r
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\n" ); document.write( "\n" ); document.write( "the range of f(x) will be all values of y > 0 and all values of y <= -.25.\r
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\n" ); document.write( "\n" ); document.write( "this can be seen on the graphs.\r
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\n" ); document.write( "\n" ); document.write( "there are 3 graphs:\r
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\n" ); document.write( "\n" ); document.write( "first graph is graph of g(x).
\n" ); document.write( "second graph is graph of f(x).
\n" ); document.write( "third graph is graph of f(x) and g(x) on the same graph.\r
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\n" ); document.write( "\n" ); document.write( "in the third graph, the values of f(x) and g(x) are shown at x = -3, x = 1, and x = 5, so you can see that the values of f(x) are the reciprocal of the values of g(x) at those values of x.\r
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\n" ); document.write( "\n" ); document.write( "this occurs at all values of x, but only those 3 values of x are shown for clarity.\r
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