Solve
(x+12)(x-10)(x+3)>0
Solution set is:
The solution of
(x+12)(x-10)(x+3) = 0
is values of x where any of the factors is zero.
That happens at x = -12, 10 and -3.
You have an inequality. It is positive when x > 10 (when all factors are positive) and between x=-3 and x= -12 (when two factors are negative and one is positive).