document.write( "Question 1192190: what are the proper steps i would need to do in order to sketch a comprehensive graph of the polynomial function f(x)=0.1x^5-0.9x^3 by showing all the necessary steps of graphing a polynomial function. \n" ); document.write( "
Algebra.Com's Answer #824123 by ikleyn(52852)\"\" \"About 
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\n" ); document.write( "what are the proper steps i would need to do in order to sketch a \"highlight%28cross%28comprehensive%29%29\" graph
\n" ); document.write( "of the polynomial function f(x)=0.1x^5-0.9x^3 by showing all the necessary steps
\n" ); document.write( "of graphing a polynomial function.
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\n" ); document.write( "\n" ); document.write( "First what you need to understand is that a sketch is not a graph.\r
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\n" ); document.write( "\n" ); document.write( "A graph must follow to a strict definition of a function and should reproduce the function literally and precisely.\r
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\n" ); document.write( "\n" ); document.write( "A sketch should only reproduce the major behavior and the major tendencies of a function.\r
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\n" ); document.write( "\n" ); document.write( "For a sketch, you should reproduce\r
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document.write( "    (a)  the zeroes of a function;\r\n" );
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document.write( "    (b)  the end behavior of a function (its behavior at x ---> oo  and  x ---> -oo);\r\n" );
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document.write( "    (c)  the asymptotical behavior of a function (horizontal and vertical asymptotes);\r\n" );
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document.write( "    (d)  local maximums and local minimums of a function;\r\n" );
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document.write( "    (e)  at the zero points (x-intercepts), you should show if the sketch (the plot) intersects x-axis and changes the sign or,\r\n" );
document.write( "         in opposite, remains the sign unchanged.\r\n" );
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\n" ); document.write( "\n" ); document.write( "If you can reproduce all these elements and peculiar properties of a function, it is just enough for the sketch.\r
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\n" ); document.write( "\n" ); document.write( "Concretely for the given function f(x) = 0.1x^5 - 0.9x^3\r
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\n" ); document.write( "\n" ); document.write( "you start by re-writing it in the equivalent form f(x) = 0.1x^3*(x^2 - 9) = 0.1x^3*(x-3)*(x+3).\r
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\n" ); document.write( "\n" ); document.write( "From this form, you see\r
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document.write( "    (a)  end behavior:  it tends to -oo  at  x ---> -oo;\r\n" );
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document.write( "                        it tends to  oo  at  x --->  oo;\r\n" );
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document.write( "    (b)  it has zeroes  at  x= 0;  x= 3;  x= -3.\r\n" );
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document.write( "    (c)  the roots are of odd multiplicities:  multiplicity 3 at x= 0;\r\n" );
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document.write( "                                               multiplicity 1 at x= -3;\r\n" );
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document.write( "                                               multiplicity 1 at x = 3.\r\n" );
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document.write( "         Hence, at each zero, the plot (the sketch) intersects x-axis, changing the sign.\r\n" );
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document.write( "    (d)  the plot is in negative half-plane y < 0 at x < -3;  \r\n" );
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document.write( "                     in positive half-plane y > 0 in the interval  -3 < x < 0;\r\n" );
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document.write( "                     in negative half-plane y < 0 in the interval  0 < x <  3;\r\n" );
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document.write( "                     in positive half-plane y > 0 in the interval  3 < x < oo.\r\n" );
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document.write( "    (e)  There is positive local maximum in the interval -3 < x < 0;\r\n" );
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document.write( "         There is negative local minimum in the interval  0 < x < 3.\r\n" );
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document.write( "I'd say, it is enough to describe the sketch for this function.\r\n" );
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\n" ); document.write( "\n" ); document.write( "What I described in this post, is not a universal prescription and is not a universal algorithm/methodology.\r
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\n" ); document.write( "\n" ); document.write( "You will get more experience with the time, when you will make sketches for 10 - 20 functions on your own . . . \r
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\n" ); document.write( "\n" ); document.write( "For periodic trigonometric functions, you should be able to describe and to reproduce their midlines; their amplitudes, periods; \r
\n" ); document.write( "\n" ); document.write( "horizontal and vertical shifts; horizontal and vertical compressing or stretching coefficients.\r
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