document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=98841>Question 98841</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I have 2 questions I need help on understanding how you get the answer, such as 4x-8 or x^2+4x-21, etc.\r<BR>\n" );
document.write( "\n" );
document.write( "A rectangle has length x+3 and width x-7. What is the area of the rectangle in terms of x.\r<BR>\n" );
document.write( "\n" );
document.write( "A virus takes up a volume of 8.5x 10^-14 cubic centimeters. Calculate the estimated number of viruses in 28 cubic centimeters.\r<BR>\n" );
document.write( "\n" );
document.write( "Thank you for your help.\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #71912 by </B><A HREF=/tutors/aboutme.mpl?userid=malakumar_kos@yahoo.com><B>malakumar_kos@yahoo.com(315)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=malakumar_kos@yahoo.com><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=71912\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "         I have 2 questions I need help on understanding how you get the answer, such as 4x-8 or x^2+4x-21, etc. <BR>\n" );
document.write( "A rectangle has length x+3 and width x-7. What is the area of the rectangle in terms of x. <BR>\n" );
document.write( "A virus takes up a volume of 8.5x 10^-14 cubic centimeters. Calculate the estimated number of viruses in 28 cubic centimeters. <BR>\n" );
document.write( "Thank you for your help. \r<BR>\n" );
document.write( "\n" );
document.write( " 1)4x-8 = 4(x-2)\r<BR>\n" );
document.write( "\n" );
document.write( " 2)x^2+4x-21 = x^2+7x-3x-21 = x(x+7)-3(x+7) = (x+7)(x-3)\r<BR>\n" );
document.write( "\n" );
document.write( " 3)Length of the rectangle L = (x+3)<BR>\n" );
document.write( "   width of the rectangle = B = (x-7)<BR>\n" );
document.write( "   Area of the rectangle = A = L.B<BR>\n" );
document.write( "                           A = (x+3).(x-7)<BR>\n" );
document.write( "                             = x^2-7x+3x-21<BR>\n" );
document.write( "                             = x^2-4x-21.\r<BR>\n" );
document.write( "\n" );
document.write( "  4)8.5x10^-14 cc of volume is occupied by 1 virus<BR>\n" );
document.write( "    28 cc of volume is occupied by ? viruses<BR>\n" );
document.write( "                    no of viruses = 28/8.5x10^-14<BR>\n" );
document.write( "                                  = 28x10^14/8.5<BR>\n" );
document.write( "                                  = 280x10^14/85<BR>\n" );
document.write( "                                  = 58x10^14/17 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );