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Relations And Functions

Question
CBSEENMA12036093

Equation of the ellipse whose axes are the axes of coordinates and which passes through the point (-3, 1) and has eccentricity square root of 2 over 5 end root is

  • 3x2 + 5y2 -32 = 0

  • 5x2 + 3y2 - 48 = 0

  • 3x2 + 5y2 - 15 = 0 

  • 5x2 + 3y2 - 32 = 0

Solution

A.

3x2 + 5y2 -32 = 0

B.

5x2 + 3y2 - 48 = 0

straight x squared over straight a squared space plus straight y squared over straight b squared space equals space 1

9 over straight a squared space plus 1 over straight b squared space equals 1...... space left parenthesis 1 right parenthesis

case - 1 when a > b
b2 = a2 (1 - e2)
b2 = a2 (1 - 2/5)
5b2 = 3a2......... (2)
from (1) & (2)
fraction numerator 9 space straight x space 3 over denominator 5 straight b squared end fraction space plus space 1 over straight b squared space equals space 1
rightwards double arrow space straight b squared space space equals 32 over 5
therefore space straight a squared space equals space 32 over 3
therefore space fraction numerator 3 straight x squared over denominator 32 end fraction space plus fraction numerator 5 straight y squared over denominator 32 end fraction space equals space 1
rightwards double arrow space 3 straight x squared space plus space 5 straight y squared minus 32
Case space minus 2
When space straight b greater than straight a
straight a squared space equals space straight b squared minus space left parenthesis 1 minus straight e squared right parenthesis
space equals space 3 over 5 space straight b squared space........ space left parenthesis 3 right parenthesis
from space left parenthesis 1 right parenthesis space & space left parenthesis 3 right parenthesis
straight a squared space equals space 48 over 5 comma space straight b squared space equals space 16
therefore space fraction numerator 5 straight x squared over denominator 48 end fraction space plus straight y squared over 16 space equals space 1
rightwards double arrow space 5 straight x squared space plus 3 straight y squared minus 48 space equals space 0

Some More Questions From Relations and Functions Chapter

If a matrix A has 12 elements, what arc the possible orders it can have 7 What if it has 7 elements ?

Let A be the set of all students of a boys school. Show that the relation R in A given by R = {(a, b) : a is sister of b} is the empty relation and R’ = {(a, b) : the difference between heights of a and b is less than 3 meters} is the universal relation.

Show that the relation R in the set {1, 2, 3} given by R = {(1, 1), (2, 2), (3, 3), (1, 2), (2, 3)} is reflexive but neither symmetric nor transitive.

Show that the relation R in the set {1, 2, 3} given by R = {(1, 2), (2, 1)} is symmetric but neither reflexive nor transitive.

Give an example of a relation which is

(i) Symmetric but neither reflexive nor transitive.
(ii) Transitive but neither reflexive nor symmetric.
(iii) Reflexive and symmetric but not transitive.
(iv) Reflexive and transitive but not symmetric.
(v) Symmetric and transitive but not reflexive.

Let L be the set of all lines in a plane and R be the relation in L defined as R = {(L1, L2) : L1 is perpendicular to L2}. Show that R is symmetric but neither reflexive nor transitive.

 Determine whether each of the following relations are reflexive, symmetric and transitive :

(i) Relation R in the set A = {1, 2, 3,....., 13, 14} defined as

R = {(x, y) : 3 x – y = 0}

(ii) Relation R in the set N of natural numbers defined as R = {(x, y) : y = x + 5 and x < 4} (iii) Relation R in the set A = {1, 2, 3, 4, 5, 6} as R = {(x,y) : y is divisible by x} (iv) Relation R in the set Z of all integers defined as R = {(x,y) : x – y is an integer}

(v) Relation R in the set A of human beings in a town at a particular time given by
(a)    R = {(x, y) : x and y work at the same place}
(b)    R = {(x,y) : x and y live in the same locality}
(c)    R = {(x, y) : x is exactly 7 cm taller than y}
(d)    R = {(x, y) : x is wife of y}
(e)    R = {(x,y) : x is father of y}

Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as R = {(a, b) : b = a + 1} is reflexive, symmetric or transitive.

Show that the relation R in R defined as R = {(a, b) : a ≤ b}, is reflexive and transitive but not symmetric.