Question 124614
The solution to the inequality x^3-4x^2-x+4(<or=)0 is
Factor to get:
(x+1)(x-1)(x-4)<=0
The zeroes are x = -1, x=1, x=4
Draw a number line; Plot those x-values.
Test a point in each of the resulting intervals to see where the solutions are.
-----------------------
If x=-2 you get: (-)(-)(-) < 0 ; true, solutions in (-inf,-1}
Since only "b" contains that information, check x=2
If x = 2 you get: (+)(+)(-) <0; true, solutions in [1,4]
-----------------
Ans: "b"
--------------------
Cheers,
Stan H.
------------------------
My answer options are:
a.[1,4]
b.(-infinity,-1]U[1,4]
c.[4,infinity)
d.[-1,1]U[4,infinity)
I thought the answer was a.,is this correct?