1) 3. 11/15 < х/15 < 4
56/15 < х/15 < 4
56/15 × 15 < х < 4 × 15
56 < х < 60
Х∈ (56;60)
2) 3. 1/8 < 25/х < 8. 1/3
25/8 < 25/х < 25/3
25 ÷ 25/8 < х < 25 ÷ 25/3
25 × 8/25 < х < 25 × 3/25
8 < х < 3
Х∈ (-∞;3) и (8;+∞).
710037|9....................................................
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<span>между ними S = 850 км
v1 = 50
v2 = 100
относительная скорость V = v1+v2 =50+100 =150 км/ч
время до встречи t = S/V = 850 / 150 = 5.7 ч</span>