JEE Advance - Mathematics (2002)

• 1

  The point(s) in the curve $${y^3} + 3{x^2} = 12y$$ where the tangent is vertical, is (are)

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  (D)

  $$\left( { \pm {4 \over {\sqrt 3 }}, 2} \right)$$
• 1

  Let $$\omega $$ $$ = - {1 \over 2} + i{{\sqrt 3 } \over 2},$$ then the value of the det.
  $$\,\left| {\matrix{ 1 & 1 & 1 \cr 1 & { - 1 - {\omega ^2}} & {{\omega ^2}} \cr 1 & {{\omega ^2}} & {{\omega ^4}} \cr } } \right|$$ is

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  (B)

  $$3\omega \left( {\omega - 1} \right)$$
• 2

  Let $$\overrightarrow V = 2\overrightarrow i + \overrightarrow j - \overrightarrow k $$ and $$\overrightarrow W = \overrightarrow i + 3\overrightarrow k .$$ If $$\overrightarrow U $$ is a unit vector, then the maximum value of the scalar triple product $$\left| {\overrightarrow U \overrightarrow V \overrightarrow W } \right|$$ is

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  (C)

  $$\sqrt {59} $$
• 2

  Let a complex number $$\alpha ,\,\alpha \ne 1$$, be a root of the equation $${z^{p + q}} - {z^p} - {z^q} + 1 = 0$$, where p, q are distinct primes. Show that either $$1 + \alpha + {\alpha ^2} + .... + {\alpha ^{p - 1}} = 0\,or\,1 + \alpha + {\alpha ^2} + .... + {\alpha ^{q - 1}} = 0$$, but not both together.

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  (A)

  The given equation can be factored, and the roots must satisfy either the p-th or q-th cyclotomic polynomial.
• 3

  If $${\overrightarrow a }$$ and $${\overrightarrow b }$$ are two unit vectors such that $${\overrightarrow a + 2\overrightarrow b }$$ and $${5\overrightarrow a - 4\overrightarrow b }$$ are perpendicular to each other then the angle between $$\overrightarrow a $$ and $$\overrightarrow b $$ is

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  (B)

  $${60^ \circ }$$
• 3

  Use mathematical induction to show that
  $${\left( {25} \right)^{n + 1}} - 24n + 5735$$ is divisible by $${\left( {24} \right)^2}$$ for all $$ = n = 1,2,...$$

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  (D)

  The inductive hypothesis is used to prove the statement for n = k+1.
• 4

  Let $$T>0$$ be a fixed real number . Suppose $$f$$ is a continuous
  function such that for all $$x \in R$$, $$f\left( {x + T} \right) = f\left( x \right)$$.

  If $$I = \int\limits_0^T {f\left( x \right)dx} $$ then the value of $$\int\limits_3^{3 + 3T} {f\left( {2x} \right)dx} $$ is

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  (C)

  $$3I$$
• 4

  Let a, b be positive real numbers. If a, $${{A_1},{A_2}}$$, b are in arithmetic progression, a, $${{G_1},{G_2}}$$, b are in geometric progression and a, $${{H_1},{H_2}}$$, b are in harmonic progression, show that $$\,{{{G_1},{G_2}} \over {{H_1},{H_2}}} = {{{A_1} + {A_2}} \over {{H_1} + {H_2}}} = {{(2a + b)\,(a + 2b)} \over {9ab}}$$.

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  (A)

  The question asks to prove an equality related to arithmetic, geometric, and harmonic progressions.
• 5

  Let $$T>0$$ be a fixed real number . Suppose $$f$$ is a continuous
  function such that for all $$x \in R$$, $$f\left( {x + T} \right) = f\left( x \right)$$.

  If $$I = \int\limits_0^T {f\left( x \right)dx} $$ then the value of $$\int\limits_3^{3 + 3T} {f\left( {2x} \right)dx} $$ is

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  (C)

  $$3I$$
• 5

  A straight line $$L$$ through the origin meets the lines $$x + y = 1$$ and $$x + y = 3$$ at $$P $$ and $$Q$$ respectively. Through $$P$$ and $$Q$$ two straight lines $${L_1}$$ and $${L_2}$$ are drawn, parallel to $$2x - y = 5$$ and $$3x + y = 5$$ respectively. Lines $${L_1}$$ and $${L_2}$$ intersect at $$R$$. Show that the locus of $$R$$, as $$L$$ varies is a straight line.

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  (A)

  The locus of R is a straight line.
• 6

  Let $$f\left( x \right) = \int\limits_1^x {\sqrt {2 - {t^2}} \,dt.} $$ Then the real roots of the equation
  $${x^2} - f'\left( x \right) = 0$$ are

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  (A)

  $$ \pm 1$$
• 6

  A straight line $$L$$ with negative slope passes through the point $$(8, 2)$$ and cuts the positive coordinate axes at points $$P$$ and $$Q$$. Find the absolute minimum value of $$OP + OQ,$$ as $$L$$ varies, where $$O$$ is the origin.

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  (C)

  18
• 7

  The integral $$\int\limits_{ - 1/2}^{1/2} {\left( {\left[ x \right] + \ell n\left( {{{1 + x} \over {1 - x}}} \right)} \right)dx} $$ equal to

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  (A)

  $$ - {1 \over 2}$$
• 7

  A triangle with vertices $$(4, 0), (-1, -1), (3, 5)$$is

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  (A)

  isosceles and right angled
• 8

  The area bounded by the curves $$y = \left| x \right| - 1$$ and $$y = - \left| x \right| + 1$$ is

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  (B)

  $$2$$
• 8

  Locus of mid point of the portion between the axes of $$x$$ $$\cos \alpha + y\sin \alpha = p$$ where $$p$$ is constant is

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  (D)

  $${1 \over {{x^2}}} + {1 \over {{y^2}}} = {4 \over {{p^2}}}$$
• 9

  For all complex numbers $${z_1},\,{z_2}$$ satisfying $$\left| {{z_1}} \right| = 12$$ and $$\left| {{z_2} - 3 - 4i} \right| = 5,$$
  the minimum value of $$\left| {{z_1} - {z_2}} \right|$$ is
  

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  (B)

  2
• 9

  If the pair of lines $$a{x^2} + 2hxy + b{y^2} + 2gx + 2fy + c = 0$$ intersect on the $$y$$ axis then

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  (A)

  $$2fgh = b{g^2} + c{h^2}$$
• 10

  The length of a longest interval in which the function $$3\,\sin x - 4{\sin ^3}x$$ is increasing, is

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  (A)

  $${\pi \over 3}$$
• 10

  The pair of lines represented by
  $$3a{x^2} + 5xy + \left( {{a^2} - 2} \right){y^2} = 0$$ are perpendicular to each other for

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  (A)

  two values of $$a$$
• 11

  Which of the following pieces of data does NOT uniquely determine an acute-angled triangle $$ABC$$ ($$R$$ being the radius of the circumcircle)?

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  (D)

  $$a,\,\sin \,A,R$$
• 11

  Prove that, in an ellipse, the perpendicular from a focus upon any tangent and the line joining the centre of the ellipse to the point of contact meet on the corresponding directrix.

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  A

  B

  C

  D
• 12

  The locus of the mid-point of the line segment joining the focus to a moving point on the parabola $${y^2} = 4ax$$ is another parabola with directrix

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  (C)

  $$x = 0$$
• 12

  Prove that $$\cos \,ta{n^{ - 1}}\sin \,{\cot ^{ - 1}}x = \sqrt {{{{x^2} + 1} \over {{x^2} + 2}}} $$.

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  (C)

  The equation can be proven with trigonometric identities and inverse trigonometric functions.
• 13

  The equation of the common tangent to the curves $${y^2} = 8x$$ and $$xy = - 1$$ is

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  (D)

  $$y= x + 2$$
• 13

  For any natural number $$m$$, evaluate
  $$\int {\left( {{x^{3m}} + {x^{2m}} + {x^m}} \right){{\left( {2{x^{2m}} + 3{x^m} + 6} \right)}^{l/m}}dx,x > 0.} $$

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  (B)

  ${1 \over 6}{{{{\left( {2{x^{3m}} + 3{x^{2m}} + 6{x^m}} \right)}^{{{m + 1} \over m}}}} \over {m + 1}} + C
• 14

  If $$a > 2b > 0$$ then the positive value of $$m$$ for which $$y = mx - b\sqrt {1 + {m^2}} $$ is a common tangent to $${x^2} + {y^2} = {b^2}$$ and $${\left( {x - a} \right)^2} + {y^2} = {b^2}$$ is

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  (A)

  $${{2b} \over {\sqrt {{a^2} - 4{b^2}} }}$$
• 14

  Find the area of the region bounded by the curves $$y = {x^2},y = \left| {2 - {x^2}} \right|$$ and $$y=2,$$ which lies to the right of the line $$x=1.$$

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  (A)

  $$\frac{20}{3} - 4\sqrt{2}$$
• 15

  If the tangent at the point P on the circle $${x^2} + {y^2} + 6x + 6y = 2$$ meets a straight line 5x - 2y + 6 = 0 at a point Q on the y-axis, then the lenght of PQ is

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  (C)

  5
• 15

  A box contains $$N$$ coins, $$m$$ of which are fair and the rest are biased. The probability of getting a head when a fair coin is tossed is $$1/2$$, while it is $$2/3$$ when a biased coin is tossed. A coin is drawn from the box at random and is tossed twice. The first time it shows head and the second time it shows tail. what is the probability that the coin drawn is fair?

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  (A)

  $$rac{9m}{m + 8N}$$
• 16

  A straight line through the origin $$O$$ meets the parallel lines $$4x+2y=9$$ and $$2x+y+6=0$$ at points $$P$$ and $$Q$$ respectively. Then the point $$O$$ divides the segemnt $$PQ$$ in the ratio

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  (B)

  $$3 : 4$$
• 16

  Let $$V$$ be the volume of the parallelopiped formed by the vectors $$\overrightarrow a = {a_1}\widehat i + {a_2}\widehat j + {a_3}\widehat k,$$ $$\,\,\,\,\overrightarrow b = {b_1}\widehat i + {b_2}\widehat j + {b_3}\widehat k,$$ $$\,\,\,\,\,\overrightarrow c = {c_1}\widehat i + {c_2}\widehat j + {c_3}\widehat k.$$ where $$r=1, 2, 3,$$ are non-negative real numbers and $$\sum\limits_{r = 1}^3 {\left( {{a_r} + {b_r} + {c_r}} \right) = 3L,} $$ show that $$V \le {L^3}\,\,.$$

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  (B)

  The maximum possible volume V is L^3.
• 17

  Let $$P = \left( { - 1,\,0} \right),\,Q = \left( {0,\,0} \right)$$ and $$R = \left( {3,\,3\sqrt 3 } \right)$$ be three points.
  Then the equation of the bisector of the angle $$PQR$$ is

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  (C)

  $$\sqrt 3 x + y = 0$$
• 18

  Let $$0 < \alpha < {\pi \over 2}$$ be fixed angle. If $$P = \left( {\cos \theta ,\,\sin \theta } \right)$$ and $$Q = \left( {\cos \left( {\alpha - \theta } \right),\,\sin \left( {\alpha - \theta } \right)} \right),$$ then $$Q$$ is obtained from $$P$$ by

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  (D)

  reflection in the line through origin with slope tan $$\left( {\alpha /2} \right)$$
• 19

  Suppose $$a, b, c$$ are in A.P. and $${a^2},{b^2},{c^2}$$ are in G.P. If $$a < b < c$$ and $$a + b + c = {3 \over 2},$$ then the value of $$a$$ is

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  (D)

  $${1 \over 2} - {1 \over {\sqrt 2 }}$$
• 20

  The number of arrangements of the letters of the word BANANA in which the two N's do not appear adjacently is

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  (A)

  40
• 21

  The sum $$\sum\limits_{i = 0}^m {\left( {\matrix{ {10} \cr i \cr } } \right)\left( {\matrix{ {20} \cr {m - i} \cr } } \right),\,\left( {where\left( {\matrix{ p \cr q \cr } } \right) = 0\,\,if\,\,p < q} \right)} $$ is maximum when $$m$$ is

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  (C)

  15
• 22

  The set of all real numbers x for which $${x^2} - \left| {x + 2} \right| + x > 0$$, is

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  (B)

  $$( - \infty ,\, - \sqrt 2 ) \cup (\sqrt 2 ,\infty )$$
• 23

  If $${a_1},{a_2}.......,{a_n}$$ are positive real numbers whose product is a fixed number c, then the minimum value of $${a_1} + {a_2} + ..... + {a_{n - 1}} + 2{a_n}$$ is

  คำตอบ

  (A)

  $$n{(2c)^{1/n}}$$
• 24

  The number of integral values of $$k$$ for which the equation $$7\cos x + 5\sin x = 2k + 1$$ has a solution is

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  (B)

  8