Gujarati
4-2.Quadratic Equations and Inequations
easy

यदि बहुपद $P(x)$ का समुच्चय S है जिसकी घात $ \le 2$ हो, जबकि $P(0) = 0,$$P(1) = 1$,$P'(x) > 0,{\rm{ }}\forall x \in (0,\,1)$, तब

A

$S = 0$

B

$S = ax + (1 - a){x^2}{\rm{ }}\forall a \in (0,\infty )$

C

$S = ax + (1 - a){x^2}{\rm{ }}\forall a \in R$

D

$S = ax + (1 - a){x^2}{\rm{ }}\forall a \in (0,2)$

(IIT-2005)

Solution

(d)माना $P(x) = b{x^2} + ax + c$

$\therefore $     $P(0) = 0 \Rightarrow c = 0$

$\therefore $    $P(1) = 1 \Rightarrow a + b = 1$

$\because$  $P(x) = ax + (1 – a){x^2}$

अब $P'(x) = a + 2(1 – a)x$

  $P'(x) > 0$ के लिए $x \in (0,\,1)$

सिर्फ विकल्प $(d)$ उपरोक्त शर्त को पूरा करता है।

Standard 11
Mathematics

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