JEE (Advanced) 2015 Paper-2

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For the following questions answer them individually

JEE (Advanced) 2015 Paper-2 - Question 41


For any integer k, let $$\alpha_k = \cos \left(\frac{k\pi}{7}\right) + i \sin \left(\frac{k\pi}{7}\right),$$ where $$i = \sqrt -1.$$ The value of the expression $$\frac{\sum_{k = 1}^{12}|\alpha_{k + 1} - \alpha_k|}{\sum_{k = 1}^{3}|\alpha_{4k - 1} - \alpha_{4k - 2}|}$$ is

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JEE (Advanced) 2015 Paper-2 - Question 42


Suppose that all the terms of an arithmetic progression (A.P.) are natural numbers. If the ratio of the sum of the first seven terms to the sum of the first eleven terms is 6: 11 and the seventh term lies in between 130 and 140, then the common difference of this A.P. is

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JEE (Advanced) 2015 Paper-2 - Question 43


The coefficient of $$x^9$$ in the expansion of $$(1 + x)(1 + x^2)(1 + x^3)...(1 + x^{100})$$ is

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JEE (Advanced) 2015 Paper-2 - Question 44


Suppose that the foci of the ellipse $$\frac{x^2}{9} + \frac{y^2}{5} = 1$$ are $$(f_1, 0)$$ and $$(f_2, 0)$$ where $$f_1 > 0$$ and $$f_3 < 0.$$ Let $$P_1$$ and $$P_2$$ be two parabolas with a common vertex at (0, 0) and with foci at $$(f_1, 0)$$ and $$(2f_2, 0),$$ respectively. Let $$T_1$$ be a tangent to $$P_1$$ which passes through $$(2f_2, 0)$$ and $$T_2$$ be a tangent to $$P_2$$ which passes through $$(f_1, 0)$$. If $$m_1$$ is the slope of $$T_1$$ and $$m_2$$ is the slope of $$T_2,$$ then the value of $$\left(\frac{1}{m_1^2} + m_2^2\right)$$ is

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JEE (Advanced) 2015 Paper-2 - Question 45


Let m and n be two positive integers greater than 1. If
$$\lim_{\alpha \rightarrow 0} \left(\frac{e^{\cos(\alpha^n)} - e}{\alpha^m}\right) = -\left(\frac{e}{2}\right)$$ then the value of $$\frac{m}{n}$$ is

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JEE (Advanced) 2015 Paper-2 - Question 46


If
$$\alpha = \int_{0}^{1} \left(e^{9x + 3 \tan^{-1}x}\right)\left(\frac{12 + 9x^2}{1 + x^2}\right) dx$$
where $$\tan^{-1}x$$ takes only principal values, then the value of $$\left(\log_e |1 + \alpha| - \frac{3\pi}{4}\right)$$ is

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JEE (Advanced) 2015 Paper-2 - Question 47


Let $$f : R \rightarrow R$$ be a continuous odd function, which vanishes exactly at one point and $$f(1) = \frac{1}{2}$$. Suppose that $$F(x) = \int_{-1}^{x} f(t) dt$$ for all $$x \in [-1, 2]$$ and $$G(x) = \int_{-1}^{x} t |f(f(t))| dt$$ for all $$x \in [-1, 2].$$ If $$\lim_{x \rightarrow 1} \frac {F(x)}{G(x)} = \frac{1}{14},$$ then the value of $$f \left(\frac{1}{2}\right)$$ is

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JEE (Advanced) 2015 Paper-2 - Question 48


Suppose that $$\overrightarrow{p}, \overrightarrow{q}$$ and $$\overrightarrow{r}$$ are three non-coplanar vectors in $$R^3$$. Let the components of a vector $$\overrightarrow{s}$$ along $$\overrightarrow{p}, \overrightarrow{q}$$ and $$\overrightarrow{r}$$ be 4, 3 and 5, respectively. If the components of this vector $$\overrightarrow{s}$$ along $$(-\overrightarrow{p} + \overrightarrow{q} + \overrightarrow{r}), (\overrightarrow{p} - \overrightarrow{q} + \overrightarrow{r})$$ and $$(-\overrightarrow{p} - \overrightarrow{q} + \overrightarrow{r})$$ are x, y and z, respectively, then the value of 2x + y + z is

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JEE (Advanced) 2015 Paper-2 - Question 49


Let S be the set of all non-zero real numbers $$\alpha$$ such that the quadratic equation $$ax^2 - x + a = 0$$ has two distinct real roots $$x_1$$ and $$x_2$$ satisfying the inequality $$|x_1 - x_2| < 1.$$ Which of the following intervals is(are) a subset(s) of S?

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JEE (Advanced) 2015 Paper-2 - Question 50


If $$\alpha = 3 \sin^{-1} \left(\frac{6}{11}\right)$$ and $$\beta = 3 \cos^{-1} \left(\frac{4}{9}\right) where the inverse trigonometric functions take only the principal values, then the correct option(s) is(are)

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