document.write( "Question 879320: Your cousin was born in the 20th century. He's x years old in the year x^2. in what year was your cousin born. \n" ); document.write( "
Algebra.Com's Answer #530671 by Edwin McCravy(20056) $\"\"$ $\"About$
You can put this solution on YOUR website!
\r\n" );
document.write( "    \r\n" );
document.write( "\r\n" );
document.write( "Since he will be x in the year x², then\r\n" );
document.write( "\r\n" );
document.write( "the year he was born is x²-x\r\n" );
document.write( "\r\n" );
document.write( "Since that was in the twentieth century, we have the inequality:\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( " and \r\n" );
document.write( " \r\n" );
document.write( "Solve each inequality separately:\r\n" );
document.write( "\r\n" );
document.write( "Solving the first inequality:\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Get critical numbers by solving\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "We need consider only positive numbers\r\n" );
document.write( "for somebody's age, so we'll use the + \r\n" );
document.write( "only.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "We use test value 44 \r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "That's false\r\n" );
document.write( "We test value 45 \r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "That's true so\r\n" );
document.write( "\r\n" );
document.write( " and since x is an integer,\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "-----------------\r\n" );
document.write( "\r\n" );
document.write( "Solve the second inequality\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Get critical numbers by solving\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Again, we need consider only positive numbers\r\n" );
document.write( "for somebody's age, so we'll use the + \r\n" );
document.write( "only.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "That is true.\r\n" );
document.write( "\r\n" );
document.write( "We use test value 46 \r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "That is false.\r\n" );
document.write( "\r\n" );
document.write( "So  and since x is an integer,\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "So the inequality is \r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Therefore x=45, and he will be 45 in the year 45² = 2025.\r\n" );
document.write( "\r\n" );
document.write( "So he was born in the year x²-x or 45²-45 = = 2025-45 = 1980.\r\n" );
document.write( "\r\n" );
document.write( "[At present he is 34 years old.  So if you know anybody who is 34\r\n" );
document.write( "years old, you can tell them that they will be x in the year x² :)  ]\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" ); document.write( "
\n" );