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) You can put this solution on YOUR website! . \n" ); document.write( "what are the proper steps i would need to do in order to sketch a \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. \n" ); document.write( "~~~~~~~~~~~~~~~~~~\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "First what you need to understand is that a sketch is not a graph.\r \n" ); document.write( " \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 \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "A sketch should only reproduce the major behavior and the major tendencies of a function.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "For a sketch, you should reproduce\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " (a) the zeroes of a function;\r\n" ); document.write( "\r\n" ); document.write( " (b) the end behavior of a function (its behavior at x ---> oo and x ---> -oo);\r\n" ); document.write( "\r\n" ); document.write( " (c) the asymptotical behavior of a function (horizontal and vertical asymptotes);\r\n" ); document.write( "\r\n" ); document.write( " (d) local maximums and local minimums of a function;\r\n" ); document.write( "\r\n" ); 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" ); document.write( "\r \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 \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Concretely for the given function f(x) = 0.1x^5 - 0.9x^3\r \n" ); document.write( " \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 \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "From this form, you see\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \r\n" ); document.write( " (a) end behavior: it tends to -oo at x ---> -oo;\r\n" ); document.write( "\r\n" ); document.write( " it tends to oo at x ---> oo;\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " (b) it has zeroes at x= 0; x= 3; x= -3.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " (c) the roots are of odd multiplicities: multiplicity 3 at x= 0;\r\n" ); document.write( "\r\n" ); document.write( " multiplicity 1 at x= -3;\r\n" ); document.write( "\r\n" ); document.write( " multiplicity 1 at x = 3.\r\n" ); document.write( "\r\n" ); document.write( " Hence, at each zero, the plot (the sketch) intersects x-axis, changing the sign.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " (d) the plot is in negative half-plane y < 0 at x < -3; \r\n" ); document.write( "\r\n" ); document.write( " in positive half-plane y > 0 in the interval -3 < x < 0;\r\n" ); document.write( "\r\n" ); document.write( " in negative half-plane y < 0 in the interval 0 < x < 3;\r\n" ); document.write( "\r\n" ); document.write( " in positive half-plane y > 0 in the interval 3 < x < oo.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( " (e) There is positive local maximum in the interval -3 < x < 0;\r\n" ); document.write( "\r\n" ); document.write( " There is negative local minimum in the interval 0 < x < 3.\r\n" ); document.write( "\r\n" ); document.write( "\r\n" ); document.write( "I'd say, it is enough to describe the sketch for this function.\r\n" ); document.write( "\r \n" ); document.write( " \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 \n" ); document.write( " \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 \n" ); document.write( " \n" ); document.write( " \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 \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |