JEE MAIN - Mathematics (2020 - 3rd September Morning Slot)

1
For the frequency distribution :
Variate (x) :      x1   x2   x3 ....  x15
Frequency (f) : f1    f2   f3 ...... f15
where 0 < x1 < x2 < x3 < ... < x15 = 10 and
$$\sum\limits_{i = 1}^{15} {{f_i}} $$ > 0, the standard deviation cannot be :
Answer
(A)
6
2
2$$\pi $$ - $$\left( {{{\sin }^{ - 1}}{4 \over 5} + {{\sin }^{ - 1}}{5 \over {13}} + {{\sin }^{ - 1}}{{16} \over {65}}} \right)$$ is equal to :
Answer
(C)
$${{3\pi } \over 2}$$
3
Let [t] denote the greatest integer $$ \le $$ t. If for some
$$\lambda $$ $$ \in $$ R - {1, 0}, $$\mathop {\lim }\limits_{x \to 0} \left| {{{1 - x + \left| x \right|} \over {\lambda - x + \left[ x \right]}}} \right|$$ = L, then L is equal to :
Answer
(B)
2
4
The solution curve of the differential equation,

(1 + e-x)(1 + y2)$${{dy} \over {dx}}$$ = y2,

which passes through the point (0, 1), is :
Answer
(D)
y2 = 1 + $${y{{\log }_e}\left( {{{1 + {e^{ x}}} \over 2}} \right)}$$
5
If $$\alpha $$ and $$\beta $$ are the roots of the equation
x2 + px + 2 = 0 and $${1 \over \alpha }$$ and $${1 \over \beta }$$ are the
roots of the equation 2x2 + 2qx + 1 = 0, then
$$\left( {\alpha - {1 \over \alpha }} \right)\left( {\beta - {1 \over \beta }} \right)\left( {\alpha + {1 \over \beta }} \right)\left( {\beta + {1 \over \alpha }} \right)$$ is equal to :
Answer
(C)
$${9 \over 4}\left( {9 - {p^2}} \right)$$
6
If the number of integral terms in the expansion
of (31/2 + 51/8)n is exactly 33, then the least value of n is :
Answer
(B)
256
7
If $$\Delta $$ = $$\left| {\matrix{ {x - 2} & {2x - 3} & {3x - 4} \cr {2x - 3} & {3x - 4} & {4x - 5} \cr {3x - 5} & {5x - 8} & {10x - 17} \cr } } \right|$$ =

Ax3 + Bx2 + Cx + D, then B + C is equal to :
Answer
(B)
-3
8
The value of (2.1P0 – 3.2P1 + 4.3P2 .... up to 51th term)
+ (1! – 2! + 3! – ..... up to 51th term) is equal to :
Answer
(D)
1 + (52)!
9
The function, f(x) = (3x – 7)x2/3, x $$ \in $$ R, is increasing for all x lying in :
Answer
(B)
$$\left( { - \infty ,0} \right) \cup \left( {{{14} \over {15}},\infty } \right)$$
10
If y2 + loge (cos2x) = y,
$$x \in \left( { - {\pi \over 2},{\pi \over 2}} \right)$$, then :
Answer
(A)
|y''(0)| = 2
11
$$\int\limits_{ - \pi }^\pi {\left| {\pi - \left| x \right|} \right|dx} $$ is equal to :
Answer
(A)
$${\pi ^2}$$
12
Consider the two sets :
A = {m $$ \in $$ R : both the roots of
x2 – (m + 1)x + m + 4 = 0 are real}
and B = [–3, 5).
Which of the following is not true?
Answer
(D)
A - B = ($$ - $$$$ \propto $$, $$ - $$3) $$ \cup $$ (5, $$ \propto $$)
13
Let P be a point on the parabola, y2 = 12x and N be the foot of the perpendicular drawn from P on the axis of the parabola. A line is now drawn through the mid-point M of PN, parallel to its axis which meets the parabola at Q. If the y-intercept of the line NQ is $${4 \over 3}$$, then :
Answer
(D)
MQ = $${1 \over 4}$$
14
The area (in sq. units) of the region

{ (x, y) : 0 $$ \le $$ y $$ \le $$ x2 + 1, 0 $$ \le $$ y $$ \le $$ x + 1,

$${1 \over 2}$$ $$ \le $$ x $$ \le $$ 2 } is :
Answer
(B)
$${{79} \over {24}}$$
15
A hyperbola having the transverse axis of length $$\sqrt 2 $$ has the same foci as that of the ellipse 3x2 + 4y2 = 12, then this hyperbola does not pass through which of the following points?
Answer
(B)
$$\left( {\sqrt {{3 \over 2}} ,{1 \over {\sqrt 2 }}} \right)$$
16
If the first term of an A.P. is 3 and the sum of its first 25 terms is equal to the sum of its next 15 terms, then the common difference of this A.P. is :
Answer
(D)
$${1 \over 6}$$
17
The lines
$$\overrightarrow r = \left( {\widehat i - \widehat j} \right) + l\left( {2\widehat i + \widehat k} \right)$$ and
$$\overrightarrow r = \left( {2\widehat i - \widehat j} \right) + m\left( {\widehat i + \widehat j + \widehat k} \right)$$
Answer
(A)
do not intersect for any values of $$l$$ and m
18
A dice is thrown two times and the sum of the scores appearing on the die is observed to be a multiple of 4. Then the conditional probability that the score 4 has appeared atleast once is :
Answer
(B)
$${1 \over 9}$$
19
If $${\left( {{{1 + i} \over {1 - i}}} \right)^{{m \over 2}}} = {\left( {{{1 + i} \over {1 - i}}} \right)^{{n \over 3}}} = 1$$, (m, n $$ \in $$ N) then the greatest common divisor of the least values of m and n is _______ .
Answer
4
20
If $$\mathop {\lim }\limits_{x \to 0} \left\{ {{1 \over {{x^8}}}\left( {1 - \cos {{{x^2}} \over 2} - \cos {{{x^2}} \over 4} + \cos {{{x^2}} \over 2}\cos {{{x^2}} \over 4}} \right)} \right\}$$ = 2-k

then the value of k is _______ .
Answer
8
21
If $$\mathop {\lim }\limits_{x \to 0} \left\{ {{1 \over {{x^8}}}\left( {1 - \cos {{{x^2}} \over 2} - \cos {{{x^2}} \over 4} + \cos {{{x^2}} \over 2}\cos {{{x^2}} \over 4}} \right)} \right\}$$ = 2-k

then the value of k is _______ .
Answer
8
22
The value of $${\left( {0.16} \right)^{{{\log }_{2.5}}\left( {{1 \over 3} + {1 \over {{3^2}}} + ....to\,\infty } \right)}}$$ is equal to ______.
Answer
4
23
Let A = $$\left[ {\matrix{ x & 1 \cr 1 & 0 \cr } } \right]$$, x $$ \in $$ R and A4 = [aij].
If a11 = 109, then a22 is equal to _______ .
Answer
10