Bất phương trình (21)x2+4x>321 có tập nghiệm là S=(a;b), khi đó b−a bằng
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$\left(\dfrac{1}{2} \right)^{x^2+4x} > \left(\dfrac{1}{2}\right)^5$
Vì $\dfrac{1}{2} < 1$ nên bất phương trình tương đương với:
$x^2 + 4x < 5$
$x^2 + 4x - 5 < 0$
$(x-1)(x+5) < 0$
$-5 < x < 1$
Vậy tập nghiệm của bất phương trình là $(-5; 1)$.
Do đó, $a = -5$ và $b = 1$. Vậy $b - a = 1 - (-5) = 1 + 5 = 6$.
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Nhận xét
Đúng
Sai
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Theo em trong Python có mấy dạng lặp:
Thiết bị nào sau đây có thể coi là vừa là thiết bị vào, vừa là thiết bị ra?
