Odpowiedź:
a)
4x² ≥ 9
x² ≥ 9/4
x² - 9/4 ≥ 0
(x - √(9/4)(x + √(9/4) ≥ 0
(x - 3/2)(x + 3/2) ≥ 0
x ≥ 3/2 ∧ x ≥ - 3/2 ∨ x ≤ 3/2 ∧ x ≤ - 3/2
x ≤ - 3/2 ∨ x ≥ 3/2
x ≤ - 1 1/2 ∨ x ≥ 1 1/2
x ∈ (- ∞ , - 1 1/2> ∪ < 1 1/2 , + ∞ )
b)
(x + 1)² + 5 > (x - 4)²
x² + 2x + 1 + 4 > x² - 8x + 16
x² + 2x + 5 > x² - 8x + 16
x² - x² + 2x + 8x + 5 - 16 > 0
10x - 11 > 0
10x > 11
x > 11/10
x > 1 1/10
x ∈ ( 1 1/10 , + ∞ )
c)
(x - 1/2)² - (x - 3/2) (x + 3/2) = 3x - 1
x² - x + 1/4 - (x² - 3²/2²) = 3x - 1
x² - x + 1/4 - x² + 9/4 = 3x - 1
- x + 10/4 = 3x - 1 | * 4
- 4x + 10 = 12x - 4
- 4x - 12x = - 4 - 10
- 16x = - 14 | * ( - 1)
16x = 14
x = 14/16 = 7/8
d)
5 - y² = 0
(√5 - y)(√5 + y) = 0
√5 - y = 0 ∨ √5 + y = 0
- y = - √5 ∨ y = - √5
y = √5 ∨ y = - √5
∨ - znaczy "lub"
∧ - znaczy "i"
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Odpowiedź:
a)
4x² ≥ 9
x² ≥ 9/4
x² - 9/4 ≥ 0
(x - √(9/4)(x + √(9/4) ≥ 0
(x - 3/2)(x + 3/2) ≥ 0
x ≥ 3/2 ∧ x ≥ - 3/2 ∨ x ≤ 3/2 ∧ x ≤ - 3/2
x ≤ - 3/2 ∨ x ≥ 3/2
x ≤ - 1 1/2 ∨ x ≥ 1 1/2
x ∈ (- ∞ , - 1 1/2> ∪ < 1 1/2 , + ∞ )
b)
(x + 1)² + 5 > (x - 4)²
x² + 2x + 1 + 4 > x² - 8x + 16
x² + 2x + 5 > x² - 8x + 16
x² - x² + 2x + 8x + 5 - 16 > 0
10x - 11 > 0
10x > 11
x > 11/10
x > 1 1/10
x ∈ ( 1 1/10 , + ∞ )
c)
(x - 1/2)² - (x - 3/2) (x + 3/2) = 3x - 1
x² - x + 1/4 - (x² - 3²/2²) = 3x - 1
x² - x + 1/4 - x² + 9/4 = 3x - 1
- x + 10/4 = 3x - 1 | * 4
- 4x + 10 = 12x - 4
- 4x - 12x = - 4 - 10
- 16x = - 14 | * ( - 1)
16x = 14
x = 14/16 = 7/8
d)
5 - y² = 0
(√5 - y)(√5 + y) = 0
√5 - y = 0 ∨ √5 + y = 0
- y = - √5 ∨ y = - √5
y = √5 ∨ y = - √5
∨ - znaczy "lub"
∧ - znaczy "i"