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   giorgiana1976 Teacher
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   First of all, find the values of x (there are 2 because of the grade of inequation) for the inequation is annulled. For this reason, we transform the above inequation into an equation.

   x^2 -4x -12 = 0

   After that, forf finding the roots of the equation, we are using the following formula:

   X1=[-b + (b^2 - 4ac)^1/2]/2a, where a=1, b=-4, c =-12

   a,b,c being the coefficients of the equation above.

   X2= [-b - (b^2 - 4ac)^1/2]/2a

   after calculation

   X1=6, X2=-2

   After that, following the rule which says that between the two roots, the values of x have the opposite sign of the "a" coefficient, and outside the roots, the values of X have the same sign with the coefficient "a", we could find the conclusion that inequation is positive on the following intervals

   (-ininite, -2) U (6, + infinite)

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   Posted by giorgiana1976 on Saturday January 31, 2009 at 10:42 AM