The number of the real solutions of the equation: x|x + 3| + |x - 1| - 2 = 0 is
- 3
- 2
- 5
- 4
Answer
(1) 3
Solution
Case 1: x 1
x(x + 3) + (x - 1) - 2 = 0 x2 + 4x - 3 = 0 x = -2 7
Neither value is 1 (-2 + 7 0.65) no root.
Case 2: -3 x < 1
x(x + 3) + (1 - x) - 2 = 0 x2 + 2x - 1 = 0 x = -1 2
-1 + 2 0.41 and -1 - 2 -2.41 both lie in [-3, 1) 2 roots.
Case 3: x < -3
-x(x + 3) + (1 - x) - 2 = 0 x2 + 4x + 1 = 0 x = -2 3
Only -2 - 3 -3.73 < -3 1 root.
number of real solutions = 0 + 2 + 1 = 3
Answer: (1)