jee-advanced

2003 mains

20 maths questions

Q1 Complex Numbers Arithmetic Modulus Inequalities and Bounds (Proof-Based) View
If $z _ { 1 }$ and $z _ { 2 }$ are two complex numbers such that $\left| \mathrm { z } _ { 1 } \right| < 1 < \left| \mathrm { z } _ { 1 } \right|$ then prove that $$\left| \frac { 1 - z _ { 1 } \bar { z } _ { 2 } } { z _ { 1 } - z _ { 2 } } \right| < 1 .$$
Q2 Straight Lines & Coordinate Geometry Full function study (variation table, limits, asymptotes) View
Find a point on the curve $x ^ { 2 } + 2 y ^ { 2 } = 6$ whose distance from the line $x + y = 7$, is minimum.
If matrix $$A = \left[ \begin{array} { l l l } a & b & c \\ b & c & a \\ c & a & b \end{array} \right]$$ where $\mathrm { a } , \mathrm { b } , \mathrm { c }$ are real positive numbers, $\mathrm { abc } = 1$ and $\mathrm { A } ^ { \mathrm { T } } \mathrm { A } = \mathrm { I }$, then find the value of $\mathrm { a } ^ { 3 } + \mathrm { b } ^ { 3 } + \mathrm { c } ^ { 3 }$.
Q4 Binomial Theorem (positive integer n) Prove a Binomial Identity or Inequality View
Prove that $$\begin{aligned} & 2 ^ { k } \binom { n } { 0 } \binom { n } { k } - 2 ^ { n - 1 } \binom { n } { 1 } \binom { n - 1 } { k - 1 } + 2 ^ { k - 2 } \\ & \binom { n } { 2 } \binom { n - 2 } { k - 2 } - \ldots \ldots \ldots ( - 1 ) ^ { k } \binom { n } { k } \binom { n - k } { 0 } = \binom { n } { k } . \end{aligned}$$
If f is an even function then prove that $$\int _ { 0 } ^ { \pi / 2 } f ( \cos 2 x ) \cos x d x = \sqrt { 2 } \int _ { 0 } ^ { \pi / 4 } f ( \sin 2 x ) \cos x d x$$
Q6 Probability Definitions Probability Using Set/Event Algebra View
For a student to qualify, he must pass at least two out of three exams. The probability that he will pass the 1st exam is P . If he fails in one of the exams then the probability of his passing in the next exam is $\mathrm { P } / 2$ otherwise it remains the same. Find the probability that he will qualify.
For the circle $x ^ { 2 } + y ^ { 2 } = t ^ { 2 }$, find the value of $r$ for which the area enclosed by the tangents drawn from the point $\mathrm { P } ( 6,8 )$ to the circle and the chord of contact is maximum.
Prove that there exists no complex number z such that $| \mathrm { z } | < 1 / 3$ and $$\sum _ { \mathrm { r } = 1 } { } ^ { \mathrm { n } } \text { at } 2 = 1 \quad \text { where } \mathrm { r } _ { \mathrm { r } } \text { as } 2 .$$
A is targeting to $\mathrm { B } , \mathrm { B }$ and C are targeting to A . Probability of hitting the target by $\mathrm { A } , \mathrm { B }$ and C are $2 / 3,1 / 2$ and $1 / 3$ respectively. If A is hit then find the probability that B hits the target and C does not.
If a function $\mathrm { f } : [ - 2 \mathrm { a } , 2 \mathrm { a } ] - - > \mathrm { R }$ is an odd function such that $\mathrm { f } ( \mathrm { x } ) = \mathrm { f } ( 2 \mathrm { a } - \mathrm { x } )$ for $\mathrm { x } \hat { \mathrm { I } } [ \mathrm { a } , 2 \mathrm { a } [$ and the left hand derivative at $\mathrm { x } = \mathrm { a }$ is 0 then find the left hand derivative at $\mathrm { x } = - \mathrm { a }$.
Using the relation $2 ( 1 - \cos x ) < x ^ { 2 } , x ^ { 1 } 0$ or otherwise, prove that $\sin ( \tan x ) > x \forall x \hat { \mathrm { I } } [ 0 , \pi / 4 ]$.
Q12 Arithmetic Sequences and Series Arithmetic-Geometric Hybrid Problem View
If $\mathrm { a } , \mathrm { b } , \mathrm { c }$ are in A.P., $\mathrm { a } ^ { 2 } , \mathrm { b} ^ { 2 } , \mathrm { c } ^ { 2 }$ are in H.P., then prove that either $\mathrm { a } = \mathrm { b } = \mathrm { c }$ or $\mathrm { a } , \mathrm { b } , - \mathrm { c } / 2$ form a G.P.
Q13 Discriminant and conditions for roots Parameter range for specific root conditions (location/count) View
If $x ^ { 2 } + ( a - b ) x + ( 1 - a - b ) = 0$ where $a , b$ Î $R$ then find the values of $a$ for which equation has unequal real roots for all values of $b$.
Normals are drawn from the point $P$ with slopes $m _ { 1 } , m _ { 2 } , m _ { 3 }$ to the parabola $y ^ { 2 } = 4 x$. If locus of $P$ with $\mathrm { m } _ { 1 } \mathrm { m} _ { 2 } = \mathrm { a }$ is a part of the parabola itself then finda.
Q15 Indefinite & Definite Integrals Definite Integral Evaluation (Computational) View
If the function $\mathrm { f } : [ 0,4 ] - - > \mathrm { R }$ is differentiable then show that (i) For $\mathrm { a } , \mathrm { b } \hat { \mathrm { I } } ( 0,4 ) , ( \mathrm { f } ( 4 ) ) ^ { 2 } = \mathrm { f } ( \mathrm { a } ) \mathrm { f } ( \mathrm { b } )$ (ii) $\left. \int _ { 0 } ^ { 4 } \mathrm { f } ( \mathrm { t } ) \mathrm { dt } = 2 \left[ \alpha \mathrm { f } \left( \alpha ^ { 2 } \right) + \beta \mathrm { f } ( \beta ) ^ { 2 } \right] \right] \forall 0 < \alpha , \beta < 2$.
(i) Find the equation of the plane passing through the points $( 2,1,0 ) , ( 5,0,1 )$ and $( 4,1,1 )$ (ii) If P is the point $( 2,1,6 )$ then the point Q such that PQ is perpendicular to the plane in (i) and the mid point of PQ lies on it.
If $\mathrm { P } ( 1 ) = 0$ and $( \mathrm { dP } ( \mathrm { x } ) ) / \mathrm { dx } > \mathrm { P } ( \mathrm { x } )$ for all $\mathrm { x } > 1$ then prove that $\mathrm { P } ( \mathrm { x } ) > 0$ for all $\mathrm { x } > 1$.
If In is the area of $n$ sided regular polygon inscribed in a circle of unit radius and On be the area of the polygon circumscribing the given circle, prove that $$I _ { n } = \frac { O _ { n } } { 2 } \left( 1 + \sqrt { 1 - \left( \frac { 2 l _ { n } } { n } \right) ^ { 2 } } \right)$$
If \overrightarrow { \mathrm { u } } , \mathrm { v } ^ { \rightarrow } , \mathrm { w } ^ { \rightarrow } are three noncoplanar unit vectors and $\alpha , \beta , \gamma$ are the angles between $\mathrm { u } \rightarrow$ are and $\mathrm { v } ^ { \rightarrow } , \mathrm { v } ^ { \rightarrow } are and $\overrightarrow { \mathrm { w } } , \mathrm { w } ^ { \rightarrow } and $\overrightarrow { \mathrm { u } }$ are respectively and $\overrightarrow { \mathrm { x } } , \mathrm { y } ^ { \rightarrow } , \mathrm { z }$ are unit vectors along the bisectors of the angles $\mathrm { a } , \mathrm { b } , \mathrm { g }$ respectively. Prove that $$\left[ \begin{array} { l l l } \vec { x } \times \vec { y } & \vec { y } \times \vec { z } & \vec { z } \times \vec { x } \end{array} \right] = \frac { 1 } { 16 } \left[ \begin{array} { l l l } \vec { u } & \vec { v } & \vec { w } \end{array} \right] ^ { 2 } \sec ^ { 2 } \frac { \alpha } { 2 } \sec ^ { 2 } \frac { \beta } { 2 } \sec ^ { 2 } \frac { \gamma } { 2 }$$
A right circular cone with radius R and height H contains a liquid which evaporates at a rate proportional to its surface area in contact with air (proportionality constant $= \mathrm { k } > 0$ ). Find the time after which the cone is empty.