document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1070259>Question 1070259</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Doctors use radioactive iodine as a tracer in diagnosing certain thyroid gland disorders.<BR>\n" );
document.write( "This type of iodine decays in such a way that the mass remaining after t days is given by the function<BR>\n" );
document.write( "m(t) = 6e<BR>\n" );
document.write( "&#8722;0.087t<BR>\n" );
document.write( "where m(t) is measured in grams.<BR>\n" );
document.write( "A) Find the initial mass (mass at time t = 0).<BR>\n" );
document.write( "B) Find the half-life. Leave the answer in exact form </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #685395 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.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/cgi-bin/show-face.mpl?user=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=685395\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This type of iodine decays in such a way that the mass remaining after t days is given by the function<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=m%28t%29+=+6e%5E%280.087t%29 ALIGN=MIDDLE  ALT=\"m%28t%29+=+6e%5E%280.087t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "where m(t) is measured in grams.<BR>\n" );
document.write( "A) Find the initial mass (mass at time t = 0).<BR>\n" );
document.write( " when t-0 we have e^0 which is equal to 1, therefore<BR>\n" );
document.write( "Initial mass is 6<BR>\n" );
document.write( ":<BR>\n" );
document.write( "B) Find the half-life. Leave the answer in exact form <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6e%5E%280.087t%29=3 ALIGN=MIDDLE  ALT=\"6e%5E%280.087t%29=3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "divide both sides by 6<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=e%5E%280.087t%29=.5 ALIGN=MIDDLE  ALT=\"e%5E%280.087t%29=.5\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "using natural logs, the log equiv of exponents is<BR>\n" );
document.write( "-.087t*ln(e) = ln(.5)<BR>\n" );
document.write( "the ln of e is 1, find the ln of .5<BR>\n" );
document.write( "-.087t = -.693<BR>\n" );
document.write( "t = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-.693%29%2F%28-.087%29 ALIGN=MIDDLE  ALT=\"%28-.693%29%2F%28-.087%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "t = 7.9672 days  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );