For x^2 - x - 12, the discriminant is ( - 1 ) ^2 - 4 * 1 * ( -12 ) = 49 => sqrt(49) = 7 =>
x1 = ( 1 + 7 ) / 2 = 4 and x2 = ( 1 - 7 ) / 2 => x2 = - 3 =>
x^2 - x - 12 = ( x - 4 )( x + 3 ) ;
In the same way, 2x^2+2x-12 = 2( x - 2 )( x + 3 );Then , (X^2-x-12) / (2x^2+2x-12) ==[ ( x - 4 )( x + 3 )] / [2( x - 2 )( x + 3 )] => ( x - 4 ) / ( 2x - 4 ), where x isn' t 2 or - 3.
