document.write( "Question 596392: the present age of john = the square of the age of his son,last year the age of john was 8 times the age of his son,what are their respective ages. \n" ); document.write( "
Algebra.Com's Answer #377747 by ankor@dixie-net.com(22740)\"\" \"About 
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let j = John's present age
\n" ); document.write( "Let s = son's present age
\n" ); document.write( ":
\n" ); document.write( "Write an equation for each statement:
\n" ); document.write( ":
\n" ); document.write( "\"the present age of john = the square of the age of his son,\"
\n" ); document.write( "j = s^2
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\n" ); document.write( "\"last year the age of john was 8 times the age of his son,\"
\n" ); document.write( "j - 1 = 8(s-1)
\n" ); document.write( "j - 1 = 8s - 8
\n" ); document.write( "j = 8s - 8 + 1
\n" ); document.write( "j = 8s - 7
\n" ); document.write( "Replace with s^2
\n" ); document.write( "s^2 = 8s - 7
\n" ); document.write( "arrange as a quadratic equation
\n" ); document.write( "s^2 - 8s + 7 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(s-7)(s-1) = 0
\n" ); document.write( "Two solutions
\n" ); document.write( "s = 1, not reasonable since a year ago he would be 0
\n" ); document.write( "s = 7 yrs is the son's age
\n" ); document.write( "then
\n" ); document.write( "j = 7^2
\n" ); document.write( "j = 49 is John's age
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\n" ); document.write( "See if that checks out in the statement:
\n" ); document.write( "\"last year the age of john was 8 times the age of his son,\"
\n" ); document.write( "49 - 1 = 8(7-1)
\n" ); document.write( "48 = 8(6)\r
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