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NTA JEE Main 24th February 2021 Shift 1 - Mathematics

For the following questions answer them individually

If $$e^{\cos^2 x + \cos^4 x + \cos^6 x + \ldots \infty} \log_e 2$$ satisfies the equation $$t^2 - 9t + 8 = 0$$, then the value of $$\frac{2\sin x}{\sin x + \sqrt{3}\cos x}$$, where $$0 < x < \frac{\pi}{2}$$, is equal to

A man is walking on a straight line. The arithmetic mean of the reciprocals of the intercepts of this line on the coordinate axes is $$\frac{1}{4}$$. Three stones A, B and C are placed at the points (1, 1), (2, 2) and (4, 4) respectively. Then which of these stones is/are on the path of the man?

Two vertical poles are 150 m apart and the height of one is three times that of the other. If from the middle point of the line joining their feet, an observer finds the angles of elevation of their tops to be complementary, then the height of the shorter pole (in meters) is:

Let $$f: R \to R$$ be defined as $$f(x) = 2x - 1$$ and $$g: R - \{1\} \to R$$. be defined as $$g(x) = \frac{x - \frac{1}{2}}{x - 1}$$. Then the composition function $$f(g(x))$$ is:

If $$f: R \to R$$ is a function defined by $$f(x) = x - 1\cos\frac{2x-1}{2}\pi$$, where $$[\cdot]$$ denotes the greatest integer function, then $$f$$ is:

The function $$f(x) = \frac{4x^3 - 3x^2}{6} - 2\sin x + (2x - 1)\cos x$$:

The population $$P = P(t)$$ at time $$t$$ of a certain species follows the differential equation $$\frac{dP}{dt} = 0.5P - 450$$. If $$P(0) = 850$$, then the time at which population becomes zero is:

The equation of the plane passing through the point (1, 2, -3) and perpendicular to the planes $$3x + y - 2z = 5$$ and $$2x - 5y - z = 7$$, is

An ordinary dice is rolled for a certain number of times. If the probability of getting an odd number 2 times is equal to the probability of getting an even number 3 times, then the probability of getting an odd number for odd number of times is:

If the least and the largest real values of $$\alpha$$, for which the equation $$z + \alpha|z - 1| + 2i = 0$$ ($$z \in C$$ and $$i = \sqrt{-1}$$) has a solution, are $$p$$ and $$q$$ respectively; then $$4(p^2 + q^2)$$ is equal to ______.

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Let $$A = \{n \in N : n \text{ is a 3-digit number}\}$$, $$B = \{9k + 2 : k \in N\}$$ and $$C = \{9k + l : k \in N\}$$ for some $$l$$ ($$0 < l < 9$$). If the sum of all the elements of the set $$A \cap (B \cup C)$$ is $$274 \times 400$$, then $$l$$ is equal to ______

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Let $$P = \begin{pmatrix} 3 & -1 & -2 \\ 2 & 0 & \alpha \\ 3 & -5 & 0 \end{pmatrix}$$, where $$\alpha \in R$$. Suppose $$Q = [q_{ij}]$$ is a matrix satisfying $$PQ = kI_3$$ for some non-zero $$k \in R$$. If $$q_{23} = -\frac{k}{8}$$ and $$Q = \frac{k^2}{2}$$, then $$\alpha^2 + k^2$$ is equal to ______.

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Let three vectors $$\vec{a}$$, $$\vec{b}$$ and $$\vec{c}$$ be such that $$\vec{c}$$ is coplanar with $$\vec{a}$$ and $$\vec{b}$$, $$\vec{a} \cdot \vec{c} = 7$$ and $$\vec{b}$$ is perpendicular to $$\vec{c}$$, where $$\vec{a} = -\hat{i} + \hat{j} + \hat{k}$$ and $$\vec{b} = 2\hat{i} + \hat{k}$$, then the value of $$2|\vec{a} + \vec{b} + \vec{c}|^2$$ is ______

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Let $$B_i$$ ($$i = 1, 2, 3$$) be three independent events in a sample space. The probability that only $$B_1$$ occur is $$\alpha$$, only $$B_2$$ occurs is $$\beta$$ and only $$B_3$$ occurs is $$\gamma$$. Let $$p$$ be the probability that none of the events $$B_i$$ occurs and these 4 probabilities satisfy the equations $$(\alpha - 2\beta)p = \alpha\beta$$ and $$(\beta - 3\gamma)p = 2\beta\gamma$$ (All the probabilities are assumed to lie in the interval (0, 1)). Then $$\frac{P(B_1)}{P(B_3)}$$ is equal to ______.

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