document.write( "Question 892243: a man is now 5 times as old as his son . Four years ago, the product of their ages was 52 . Find their present ages
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Algebra.Com's Answer #540750 by LinnW(1048)\"\" \"About 
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set m = man's age
\n" ); document.write( " s = son's age
\n" ); document.write( "m = 5s
\n" ); document.write( "(m-4)(s-4) = 52
\n" ); document.write( "substitute 5s for m in the above
\n" ); document.write( "(5s-4)(s-4) = 52
\n" ); document.write( "5s^2 -20s -4s + 16 = 52
\n" ); document.write( "5s^2 -24s + 16 = 52
\n" ); document.write( "add -54 to each side
\n" ); document.write( "5s^2 -24s -36 = 0
\n" ); document.write( "We want two numbers whose product is -180 and whose sum is -24.
\n" ); document.write( "-30 and 6 work for this.
\n" ); document.write( "5s^2 -30s +6s -36 = 0
\n" ); document.write( "factor by grouping
\n" ); document.write( "5s(s - 6) +6(s - 6) = 0
\n" ); document.write( "(5s + 6)(s - 6) = 0
\n" ); document.write( "So 5s + 6 = 0 or s - 6 = 0
\n" ); document.write( "For 5s + 6 = 0 , add -6 to each side
\n" ); document.write( " 5s = -6
\n" ); document.write( "divide each side by 5
\n" ); document.write( " s = -6/5
\n" ); document.write( "For s -6 = 0
\n" ); document.write( "add 6 to each side
\n" ); document.write( " s = 6
\n" ); document.write( "We need a positive number so the son's age is 6
\n" ); document.write( "Since m = 5s , m = 5(6) = 30 \n" ); document.write( "
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