A) Here is solution for - Wolfram|Alpha
1. Solve (x+1)(x-2)(x-4)^2 = 0
As you can see we have 3 roots here: . It means function changes it's sign in this points.
2. Find sign of y in following intervals by selecting random value and evaluating y: (-inf, -1), (-1, 2), (2, 4) and (4,+inf).
3. Select intervals where y > 0
Note that is never negative.A) Solve for
So we are concerned with and only.
The product is greater than or equal to zero in two cases:
. . (1) Both factors are positive
. . (2) Both factors are negative
Case 1: .
Case 2: .