Решите неравенство:
|х-14| меньше, либо равно 8+2х
|х+5| > 5х-7
|х^2+х-5| > 3х
1) |х-14|≤ 8+2х
a) x-14 ≤ 8+2x
-x≤22
x≥-22
b) -x+14≤8+2x
-3x≤-6
x≥2
x ∈ [2; +∞)
2) |х+5| > 5х-7
a) x+5 > 5x - 7
-4x > -12
x < 3
b) -x-5 > 5x-7
-6x > -2
x < 1/3
x ∈ (-∞; 1/3)
3) |х^2+х-5| > 3х
a) x² + x -5 > 3x
x² - 2x - 5 > 0
x² - 2x - 5 = 0
D = 4 + 20 = 24
x₁ = (2+2√6)2 = 1 + √6
x₂ = 1 - √6
x ∈ (-∞; 1 - √6) U ( 1 + √6; +∞)
b) -x² - x + 5 > 3x
-x² - 4x + 5 > 0
x² + 4x - 5 > 0
x² + 4x - 5 = 0
x₁ = 1
x₂ = -5
x ∈ (-∞; -5) U (1; +∞)
x ∈ (1 - √6; 1)
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Answers & Comments
1) |х-14|≤ 8+2х
a) x-14 ≤ 8+2x
-x≤22
x≥-22
b) -x+14≤8+2x
-3x≤-6
x≥2
x ∈ [2; +∞)
2) |х+5| > 5х-7
a) x+5 > 5x - 7
-4x > -12
x < 3
b) -x-5 > 5x-7
-6x > -2
x < 1/3
x ∈ (-∞; 1/3)
3) |х^2+х-5| > 3х
a) x² + x -5 > 3x
x² - 2x - 5 > 0
x² - 2x - 5 = 0
D = 4 + 20 = 24
x₁ = (2+2√6)2 = 1 + √6
x₂ = 1 - √6
x ∈ (-∞; 1 - √6) U ( 1 + √6; +∞)
b) -x² - x + 5 > 3x
-x² - 4x + 5 > 0
x² + 4x - 5 > 0
x² + 4x - 5 = 0
x₁ = 1
x₂ = -5
x ∈ (-∞; -5) U (1; +∞)
x ∈ (1 - √6; 1)