document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=423339>Question 423339</A>: <I><SPAN STYLE=\"word-break: break-all;\"> -90(t) + 4.905 (t*t) -150 = 19.9! !!           can u explain to me how they found t=19.9 ? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #295288 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=295288\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> if i understood your question correctly, you have a formula that is:\r<BR>\n" );
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document.write( "4.905*t^2 - 90*t - 150 = 0\r<BR>\n" );
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document.write( "you want to find the roots of this equation.\r<BR>\n" );
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document.write( "you use the quadratic formula.\r<BR>\n" );
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document.write( "this give you an answer of:\r<BR>\n" );
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document.write( "x = 19.88641 <BR>\n" );
document.write( "or:<BR>\n" );
document.write( "x = -1.53779\r<BR>\n" );
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document.write( "round these to the nearest 10th and you get:\r<BR>\n" );
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document.write( "x = 19.9 <BR>\n" );
document.write( "or:<BR>\n" );
document.write( "x = -1.5\r<BR>\n" );
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document.write( "the 19.9 looks like the number you are showing.\r<BR>\n" );
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document.write( "from what i can see, it is one of the roots of the quadratic equation of:\r<BR>\n" );
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document.write( "4.905*t^2 - 90*t - 150 = 0\r<BR>\n" );
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document.write( "the standard form of a quadratic equation is:\r<BR>\n" );
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document.write( "ax^2 + bx + c = 0\r<BR>\n" );
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document.write( "this makes:\r<BR>\n" );
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document.write( "a = 4.905<BR>\n" );
document.write( "b = -90<BR>\n" );
document.write( "c = -150\r<BR>\n" );
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document.write( "the quadratic formula give you:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-b+%2B-+sqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x+=+%28-b+%2B-+sqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "you solve by plugging in the values for a,b,c derived from above.\r<BR>\n" );
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document.write( "the values of x = 19.9 and x = -1.5 are the roots of the quadratic equation.\r<BR>\n" );
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document.write( "these are the value of x when the graph of the equation crosses the x-axis.\r<BR>\n" );
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document.write( "the graph of your equation of y = 4.905*t^2 - 90*t - 150 looks like this:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28600%2C600%2C-5%2C25%2C-800%2C800%2C4.905%2Ax%5E2+-+90%2Ax+-+150%29 ALIGN=MIDDLE  ALT=\"graph%28600%2C600%2C-5%2C25%2C-800%2C800%2C4.905%2Ax%5E2+-+90%2Ax+-+150%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( " </SPAN>\n" );
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