document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1106911>Question 1106911</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A model rocket is launched from the ground with an inital velocity of 68 m/s. The function h = -4.9t + 68t models the height of the rocket in metres after t seconds. At what time is the rocket above 72 m above the ground? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #721910 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52781)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=721910\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "A model rocket is launched from the ground with an inital velocity of 68 m/s. The function h = -4.9t + 68t models the height <BR>\n" );
document.write( "of the rocket in metres after t seconds. At what time is the rocket above 72 m above the ground?<BR>\n" );
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document.write( "You &nbsp;<U>INCORRECTLY</U>&nbsp; presented your function.\r<BR>\n" );
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document.write( "The correct form is  h = -4.9t^2 + 68t.     &nbsp;&nbsp;&nbsp;&nbsp;It is the standard form when the unit of length/distance  &nbsp;<U>the\"foot\"</U>&nbsp; is used.\r<BR>\n" );
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document.write( "To answer the question, you need to solve the quadratic equation\r<BR>\n" );
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document.write( "-4.9*t^2 + 68t = 72.<BR>\n" );
document.write( "</pre>\r<BR>\n" );
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document.write( "To see many other similar solved problems, look into the lessons\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-projectile-moving-vertically.lesson>Problem on a projectile moving vertically up and down</A>\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-projectile-shooted-vertically-upward.lesson>Problem on an arrow shot vertically upward</A>\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/word/travel/Typical-problems-on-an-projectile-moving-vertically-up-and-down.lesson>Problem on a ball thrown vertically up from the top of a tower</A> \r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-toy-rocket-launched-vertically-up--from-the-top-of-a-platform.lesson>Problem on a toy rocket launched vertically up from a tall platform</A>\r<BR>\n" );
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document.write( "Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.\r<BR>\n" );
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document.write( "The referred lessons are the part of this textbook under the topic \"<U>Projectiles launched/thrown and moving vertically up and dawn</U>\".\r<BR>\n" );
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document.write( "Save the link to this online textbook together with its description\r<BR>\n" );
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document.write( "Free of charge online textbook in ALGEBRA-I<BR>\n" );
document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r<BR>\n" );
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document.write( "to your archive and use it when it is needed.\r<BR>\n" );
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document.write( "Be aware !  The solution by &nbsp;@addingup &nbsp;is &nbsp;&nbsp;<U>I N C O R R E C T  &nbsp;!</U>.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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