2. а)
- + +
-------o///////o////////-> ⇒ x∈(-3; 3)∪(3; +∞)
-3 3
Ответ: (-3; 3)∪(3; +∞).
б) (x²-6x+8)² + (x²-6x+8) < 0
(x²-6x+8)(x²-6x+8+1) < 0
(x²-6x+8)(x²-6x+9) < 0
(x-2)(x-4)(x-3)² < 0
+ - - +
-------o///////o///////o-------> ⇒ x∈(2; 3)∪(3; 4)
2 3 4
Ответ: (2; 3)∪(3; 4).
3. а)
-///////o///////o///////o/////////-> ⇒ x∈(-∞; -2)∪(-2; 0)∪(0; 2)∪(2; +∞)
-2 0 2
Ответ: (-∞; -2)∪(-2; 0)∪(0; 2)∪(2; +∞).
б) (x²-2x-7)² - (x²-6x-3) < 0
(x²-2x-7-x²+6x+3)(x²-2x-7+x²-6x-3) < 0
(4x-4)(2x²-8x-10) < 0
8(x-1)(x²-4x-5) < 0
(x-1)(x+1)(x-5) < 0
- + - +
-------o///////o///////o-------> ⇒ x∈(-∞; -1)∪(1; 5)
-1 1 5
Ответ: (-∞; -1)∪(1; 5).
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Answers & Comments
2. а)
- + +
-------o///////o////////-> ⇒ x∈(-3; 3)∪(3; +∞)
-3 3
Ответ: (-3; 3)∪(3; +∞).
б) (x²-6x+8)² + (x²-6x+8) < 0
(x²-6x+8)(x²-6x+8+1) < 0
(x²-6x+8)(x²-6x+9) < 0
(x-2)(x-4)(x-3)² < 0
+ - - +
-------o///////o///////o-------> ⇒ x∈(2; 3)∪(3; 4)
2 3 4
Ответ: (2; 3)∪(3; 4).
3. а)
-///////o///////o///////o/////////-> ⇒ x∈(-∞; -2)∪(-2; 0)∪(0; 2)∪(2; +∞)
-2 0 2
Ответ: (-∞; -2)∪(-2; 0)∪(0; 2)∪(2; +∞).
б) (x²-2x-7)² - (x²-6x-3) < 0
(x²-2x-7-x²+6x+3)(x²-2x-7+x²-6x-3) < 0
(4x-4)(2x²-8x-10) < 0
8(x-1)(x²-4x-5) < 0
(x-1)(x+1)(x-5) < 0
- + - +
-------o///////o///////o-------> ⇒ x∈(-∞; -1)∪(1; 5)
-1 1 5
Ответ: (-∞; -1)∪(1; 5).