document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1130918>Question 1130918</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The worlds biggest  led screen is in a small mall in Bejing, China its length is ten meters more than eight times in width. the total screen area is a whooping 7,500 square meters  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #747571 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13198)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=747571\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "If you try to solve this problem using formal algebra, you end up having to solve the quadratic equation<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=8x%5E2%2B10x-7500+=+0 ALIGN=MIDDLE  ALT=\"8x%5E2%2B10x-7500+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Of course you can always solve a quadratic equation using the quadratic formula.  But if you try to solve by factoring, there is a lot of trial and error in the process.<br><BR>\n" );
document.write( "The problem is solved far more easily (if a formal algebraic solution is not required!) by doing the trial and error with the given information: find two numbers whose product is 7500 that satisfy the condition that one number is 10 more than 8 times the other.<br><BR>\n" );
document.write( "We don't need to do blind guessing; we can make some useful approximations.<br><BR>\n" );
document.write( "We can make the approximation that the longer side is 8 times the shorter side instead of 10m more than 8 times as long.<br><BR>\n" );
document.write( "Then the approximate equation is 8x^2=7500, and we can approximate that with 8x^2=8000, or x^2=1000.<br><BR>\n" );
document.write( "Then we can see that x should be a number close to 30.<br><BR>\n" );
document.write( "And 30 times 250 is 7500; and 250 is 10 more than 8 times 30.<br><BR>\n" );
document.write( "If your mental arithmetic is good, solving the problem like that is much less work than using formal algebra. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );