Solve the inequation: x^2-4x-12>0

   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, for 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

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