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<Worksheet><Version major="6" minor="0"/><View-Properties><Zoom percentage="100"/></View-Properties><Styles><Layout alignment="left" bullet="none" firstindent="0.0" leftmargin="0.0" linebreak="space" name="Normal" rightmargin="0.0" spaceabove="0.0" spacebelow="0.0"/><Layout alignment="centred" bullet="none" linespacing="0.5" name="Maple Output"/><Font background="[0,0,0]" bold="false" executable="false" family="Times New Roman" foreground="[0,0,0]" italic="false" name="Text" opaque="false" size="12" underline="false"/><Font background="[0,0,0]" executable="true" family="Times New Roman" foreground="[255,0,0]" name="2D Input" opaque="false" size="12"/><Font background="[0,0,0]" family="Times New Roman" foreground="[0,0,255]" name="2D Output" opaque="false" readonly="true" size="12"/><Font background="[0,0,0]" bold="true" executable="true" family="Monospaced" foreground="[255,0,0]" name="Maple Input" opaque="false" size="12"/></Styles><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">For a less trivial example, let us find the REAL solutions of F = G = 0, where</Font></Text-field><Text-field layout="Normal" style="Text"/><Text-field layout="Normal" prompt="&gt; " style="Maple Input">G:=x^6+3*x^4*y^2-(30003*x^4)/10000+3*x^2*y^4-(30003*x^2*y^2)/5000+(300060003*x^2)/100000000+y^6-(30003*y^4)/10000+(300060003*y^2)/100000000-1000300030001/1000000000000;</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation>NiM+SSJHRzYiLDYqJEkieEdGJSIiJyIiIiomRigiIiVJInlHRiUiIiMiIiQqJEYoRiwjISYuKyQiJisrIiomRihGLkYtRixGLyomRihGLkYtRi4jRjIiJStdKiRGKEYuIyIqLisxKyQiKisrKysiKiRGLUYpRioqJEYtRixGMSokRi1GLkY5IyEuLCsuKy4rIiIuKysrKysrIkYq</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" prompt="&gt; " style="Maple Input">F:=  27+171*y^2+66*x^2*y^2-72*x^2*y+3*x^4*y^2-12*x^4*y+3*x^
2*y^4-24*x^2*y^3+27*x^2-108*y+9*x^4+57*y^4-136*y^3
+x^6+y^6-12*y^5;</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation>NiM+SSJGRzYiLEIiI0YiIiIqJEkieUdGJSIiIyIkciIqJkkieEdGJUYrRipGKyIjbSomRi5GK0YqRighI3MqJkYuIiIlRipGKyIiJComRi5GM0YqRighIzcqJkYuRitGKkYzRjQqJkYuRitGKkY0ISNDKiRGLkYrRidGKiEkMyIqJEYuRjMiIioqJEYqRjMiI2QqJEYqRjQhJE8iKiRGLiIiJ0YoKiRGKkZDRigqJEYqIiImRjY=</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">Before we use resultants let us blindly try the numerical routine included in Maple.  To do this, we enter the command </Font></Text-field><Text-field layout="Normal" style="Text"/><Text-field layout="Normal" prompt="&gt; " style="Maple Input">p:=solve({F,G1},{x,y});</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation style="2D Output">NiM+SSJwRzYiPCQvSSJ5R0YlIyImLCslIiYrKyUvSSJ4R0YlLCQtSSdSb290T2ZHNiRJKnByb3RlY3RlZEdGMkkoX3N5c2xpYkdGJTYkLCYqJEkjX1pHRiUiIiMiIiIhJioqKnpGOS9JJmxhYmVsR0YxSSVfTDEwR0YlI0Y5Ris=</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">And if you use evalf to numerically evaluate this result, we obtain </Font></Text-field><Text-field layout="Normal" style="Text"/><Text-field layout="Normal" prompt="&gt; " style="Maple Input">evalf({p});</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation style="2D Output">NiM8IzwkL0kieEc2IiQiKz1PLXJxISM3L0kieUdGJyQiKytdLSs1ISIq</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">On the other hand we can ask maple to calculate the resultant of F and G with respect to x. One gets </Font></Text-field><Text-field layout="Normal" style="Text"/><Text-field layout="Normal" prompt="&gt; " style="Maple Input">R1:=resultant(F,G1,x);</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation style="2D Output">NiM+SSNSMUc2IiokLDYqJEkieUdGJSIiKiInV0BFKiRGKSIiKSMhK2tvZnU5IiREJyokRikiIigjIi4vQkslZSdvJCInRDFSKiRGKSIiJyMhMSUzITM1S1N3YCIqRDE5VyMqJEYpIiImIyI2aiszNVtnR2hIaCIiLisrXTdHKVsqJEYpIiIlIyE6aitnNyEzNUtTaytfayIzKysrKytdN2A+KiRGKSIiJCMiPkArLzBTXSEpb1UxSyEqR2cpIjcrKysrKysrK0QxUiokRikiIiMjIUM0K18tQ0lnLFUxV05uIT1bWiIiPCsrKysrKysrKysrRGMiRikjIkc0KylHPy5rREtHQDZPQzd2PiUqKmUiQSsrKysrKysrKysrKysrK0QjIUssK08rdzB3YGNBRiFwMiVlKUgpKUg/aSMiRisrKysrKysrKysrKysrKysrKyIiIiJGSw==</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">This unwieldy polynomial can be simplified by typing</Font></Text-field><Text-field layout="Normal" style="Text"/><Text-field layout="Normal" prompt="&gt; " style="Maple Input">factor(R1);</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation style="2D Output">NiMsJCokLCYhJiwrJSIiIkkieUc2IiImKyslIiM9I0YnImRvKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrIg==</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">Therefore, 40001/40000 is the y-coordinate of some solution of F = G = 0 (why ?).  We can now find the x-coordinate.  To do this we substitute this value back into both equations, and find the common roots.  We first substitute in F and factor.  The Maple command is</Font></Text-field><Text-field layout="Normal" style="Text"/><Text-field layout="Normal" prompt="&gt; " style="Maple Input">factor(subs(y=40001/40000,F));</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation style="2D Output">NiMsJCokLCYqJEkieEc2IiIiIyIrKysrKzshJioqKnoiIiIiIiQjRiwiPSsrKysrKysrKysrKyc0JQ==</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" prompt="&gt; " style="Maple Input">factor(subs(y=40001/40000,G1));</Text-field></Input><Output><Text-field layout="Maple Output" style="2D Output"><Equation style="2D Output">NiMsJCokLCYqJEkieEc2IiIiIyIrKysrKzshJioqKnoiIiIiIiQjRiwiPSsrKysrKysrKysrKyc0JQ==</Equation></Text-field></Output></Group><Group><Input><Text-field layout="Normal" style="Text"><Font size="14">so (</Font><Equation executable="true" input-equation="\sqrt(79999/1600000000)" style="2D Input">NiMtSSVzcXJ0RzYiNiMqJiImKioqeiIiIiIrKysrKzshIiI=</Equation>  ,<Equation executable="true" input-equation="40001/40000" style="2D Input">NiMqJiImLCslIiIiIiYrKyUhIiI=</Equation><Font size="14">) and (</Font><Equation executable="true" input-equation="-sqrt(79999/1600000000)" style="2D Input">NiMsJC1JJXNxcnRHNiI2IyomIiYqKip6IiIiIisrKysrOyEiIkYs</Equation><Font size="14"> , </Font><Equation executable="true" input-equation="40001/40000" style="2D Input">NiMqJiImLCslIiIiIiYrKyUhIiI=</Equation><Font size="14">) are the two REAL solutions of our system.  In fact, these are the only COMPLEX solutions as well.  Note that <Font bold="true">solve</Font> gave an expression for both solutions, but <Font bold="true">evalf</Font> gave (an approximation to) only
 one solution.</Font></Text-field><Text-field layout="Normal" style="Text"/></Input></Group><Text-field/><Text-field/><Text-field/><Text-field/></Worksheet>