document.write( "Question 678811: A is thrice as old as his son. In ten years, the product of their ages will be 800.How old are they now ? \n" ); document.write( "

Algebra.Com's Answer #421858 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A is thrice as old as his son.
\n" ); document.write( "a = 3s
\n" ); document.write( ":
\n" ); document.write( "In ten years, the product of their ages will be 800.
\n" ); document.write( "(a+10)(s+10) = 800
\n" ); document.write( "Foil
\n" ); document.write( "as + 10a + 10s + 100 = 800
\n" ); document.write( "as + 10a + 10s - 700 = 0
\n" ); document.write( "Replace a with 3s
\n" ); document.write( "3s*s + 10(3s) + 10s - 700 = 0
\n" ); document.write( "3s^2 + 30s + 10s - 700 = 0
\n" ); document.write( "A quadratic equation
\n" ); document.write( "3s^2 + 40s - 700 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(3s+70)(s-10) = 0
\n" ); document.write( "The positive solution
\n" ); document.write( "s = 10 yrs is the son's age
\n" ); document.write( ":
\n" ); document.write( "You can find A's age. Check solution in the statement:
\n" ); document.write( "\"In ten years, the product of their ages will be 800.\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "How old are they now ? \n" ); document.write( "

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