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\"joe said, if five times my age in 8 years is subtracted from the square of my present age, the result is 86.\" find joe's age\r
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\n" ); document.write( "\n" ); document.write( "let joe's present age be x
\n" ); document.write( "so joe's age 8 yrs to this the present time will be x+8,\r
\n" ); document.write( "\n" ); document.write( "now that means 5* joe's age in 8yrs is 5(x+8)
\n" ); document.write( "the square of his present age is x^2
\n" ); document.write( "therefore we can hereby write that
\n" ); document.write( "X^2-5(x+8)=86: expanding the bracket we'll have\r
\n" ); document.write( "\n" ); document.write( "X^2-5x-40=86\r
\n" ); document.write( "\n" ); document.write( "x^2-5x-40-86=0\r
\n" ); document.write( "\n" ); document.write( "x^2-5x-126=0\r
\n" ); document.write( "\n" ); document.write( "can you predict the factors of this quadratic equation?\r
\n" ); document.write( "\n" ); document.write( "try\r
\n" ); document.write( "\n" ); document.write( "it\"s 14 and 9\r
\n" ); document.write( "\n" ); document.write( "x^2-14x+9x-126=0
\n" ); document.write( "x(x-14)+9(x-14)=0
\n" ); document.write( "(x+9)(x-14)=0\r
\n" ); document.write( "\n" ); document.write( "either x+9=0 or x-14=0
\n" ); document.write( "the first option gives x=-9 while the second gives x as 14\r
\n" ); document.write( "\n" ); document.write( "since joe's age cannot be negative, joe's present age is 14yrs\r
\n" ); document.write( "\n" ); document.write( "hope you understand the tricks
\n" ); document.write( "look into your maths book or this site and solve related problems to perfect your skills. \n" ); document.write( "