2. Monotone subtraction interval: (negative infinity,-2)&; (0,2)
Monotonically increasing interval: (-2,0)&; (2, positive infinity)
3.? K & lt- 1,? No answer
K=- 1,? Two solutions
- 1 & lt; K<3 and 4 solutions
K=3,? Three solutions
k & gt3? , 2 solutions
1, chasing dreams and seeking fate
2. Patience and backbone
Step 3 live bravely
4. Ideal wings
Step