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6901.

If A and B are invertible matrices of same order then prove that (AB)^(-1) = B^(-1)A^(-1)

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ANSWER :`(AB)^(-1) = B^(-1)A^(-1)`
6902.

The three sides of a trapezium are equal, each being 6 cm long. Find the area of trapezium when it is maximum.

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ANSWER :`27sqrt(3)` sq.cm.
6903.

Let r be the range and S^(2)=(1)/(n-1) sum_(i=1)^(n) (x_(i)-overline(x))^(2) be the SD of a set of observations x_(1),x_(2),.., x_(n), then

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`S le r sqrt((N)/(n-1))`
`S=r sqrt((n)/(n-1))`
`S ge r sqrt((n)/(n-1))`
None of these

Solution :We have r=max `|x_(i)-x_(j)|`
and `S^(2)=(1)/(n-1) underset(i=1)OVERSET(n)(sum)(x_(i)-overline(x))^(2)`
Now, `(x_(i)-overline(x))^(2)=(x_(i)-(x_(1)+x_(2)+..+x_(n))/(n))^(2)`
`=(1)/(n^(2))[(x_(i)-x_(1))+(x_(i)-x_(2))+..+(x_(i)-x_(i)-1)+(x_(i)-x_(1)+1)+..+(x_(i)-x_(n))] le (1)/(n^(2))[(n-1)r]^(2) "" [because]x_(i)-x_(j)|le r|`
`(x_(i)-overline(x))^(2) le r^(2)`
`implies underset(i=1)overset(n)(sum)(x_(i)overline(x))^(2) le NR^(2)`
`implies (1)/(n-1) underset(i=1)overset(n)(sum)(x_(i)-overline(x))^(2) le(nr^(2))/((n-1))`
`implies S^(2) le (nr^(2))/((n-1))`
`implies S le r sqrt((n)/(n-1))`
6904.

Natural numbers k,l,p and q are such that if a and b are roots of x^(2) - kx + l=0, then a+1/b and b+1/a are roots of x^(2) -px + q=0. What is the sum of all possible values of q?

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ANSWER :4
6905.

Two particles P and Q located at the points with coordinates P(t^3-16t-3),Q(t+1,t^3-6t-6) are moving in a plane. The minimum distance between them in their motion is

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1
5
169
49

Answer :D
6906.

What is the standard enthalpy change at 298 K for the following reaction? CO_(2) (g)+ C("diamond") rarr 2CO(g) Given : DeltaH_(f)^(@)(CO,g) = - 110.5 kJ//mol : Delta H_(f)^(@)(CO_(2),g) = - -393.5 kJ//mol Delta H_("transition")^(@)[C("graphite")rarr C("diamond")] = 2.0 kJ//mol

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`-172.5 kJ//mol`
`-170.5 kJ//mol`
`+172.5 kJ//mol`
`170.5 kJ//mol`

ANSWER :D
6907.

Draw the graph of y = sin pisqrt(x).

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Solution :We have `y = f(X) = sin pisqrt(x)`
Clearly, the domain of the function is `[0, oo).`
`sin pi sqrt(x) = 0`
`therefore` `pi sqrt(x) = n pi, n in Z`
`therefore` `x = n^(2), n in Z`
Also `sin pi sqrt(x) GT 0`
`therefore` `pi sqrt(x) in underset(n = 1)overset(oo)UUU (2npi, (2N + 1)pi)`
`therefore` `x in underset(n = 1)overset(oo)uuu (4n^(2), (2n + 1)^(2))`
Similarly, sin `pi sqrt(x) lt 0` for `x in underset(n in z^(+))uuu ((2n + 1)^(2), (2n + 2)^(2))`
Thus, the graph of the function is as follows.
6908.

Line A passes through the cooredinate points (-2/5, 0) and (0,1). Which of the following lines will line A never intersect ?

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Solution :You're asked to identify the line that the one discribed in the EQUATION stem will never intersect. Lines that never intersect are parallel and therefore have identical slopes, so stary by finding the SLOPE of the line WHOSE two cordinate pairs are given. You'll find:
`m =(1-0)/(0-(-(2)/(5)))=(1)/((2)/(5))=5/3`
Choice (C ) and (D) have negative slopes, so eliminate them. Next, find the slopes of (A) and (B). No need to use the slope formula, counting units on the GRAPHS will be faster.The slope of (A) is `2/5` because for every 2 units the line rises, it RUNS 5 units to the right. The slope of (B) is `5/2` because when the line goes up 5 units, it goes 2 units to the right. Therefore (B) is correct.
6909.

A cyclist covers his first three miles at an average speed of 8 m.p.h. Anoter two miles at 3m.p.h. and the last two miles at 2m.p.h. The average speed for the entire journey is : (in m.p.h)

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3
2.4
3.8
3.43

Answer :D
6910.

Find the coordinates of the mid-point of the following pairs of points .(-7,3), (8,-4) .

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Solution :Mid POINTS of the line SEGMENT JOINING the points (-7,3) and (8,-4) is
`((-7+8)/2,(3-4)/2)=(1/2,-1/2)`.
6911.

If cos x=|sinx| then, the general solution is

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a.`x=npi+(-1)^(N)pi/4,n in Z`
B.`x=npi+-pi/4,n in Z`
C.`x=(2n+1)pi+-pi/4,n in Z`
d.`x=2npi+-pi/4, n in Z`

Answer :D
6912.

Find the derivative of x^(3) from the first principle.

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ANSWER :`3X^(2)`.
6913.

Let [ x ] denote the largest integer le x. If the number of solutions of cos^(2)theta is k, then for x in [pi/4,pi/3] the value of k^(tan^(2)x)

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is equal to 1
LIES in between `2^(1) and 2^(3)`
is equal to ZERO
lies in between `1/2^(3) and 1/2`

Answer :C
6914.

If a function f is defined by : f(x) = 0, when x = 1, = x^(3) - 1, when 1 lt x lt oo, = x - 1, when -oo lt x lt 1, then at x = 1, f is

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CONTINUOUS and differentiable
continuous but not differentiable
discontinuous and differentiable
discontinuous and not differentiable

Answer :B
6915.

int(sin 2x)/(sin5x*sin3x)dx=.....+c

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`log|sin3x|-log|sin5x|`
`(1)/(3)log|sinx3x|+(1)/(5)|SIN 5x|`
`(1)/(3)log|sinx3x|-(1)/(5)|sin 5x|`
`3 log|sin3x|-5(1)/(5)log|sin 5x|`

ANSWER :C
6916.

For any two statements p and q, the statement ~(p ^^ q) vee (~p ^^ q) is equivalent to

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~p
p
q
p `^^` q

Answer :A
6917.

Find the number of ways to arrange 5 boys and 5 girl in a row such that no two girls sit together

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ANSWER :`lfloor5xx^6P_5`
6918.

Let a_n = int_(0)^(pi//2) (1-cos2npi)/(1-cos2pi)dx The value of |{:(pi//2 , a_2 , a_3),(a_4 ,a_5, a_6),(a_7 , a_8 , a_9):}|=

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0
1
3
None of these

Answer :A
6919.

State which of the following are positive ? cot 375^@

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Solution :`COT 375^@` is +ve as `375^@` LIES in 1st quadrant.
6920.

int_(0)^(1) sin (2 tan^(-1) sqrt((1+x)/(1-x))) dx is equal to

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`PI/6`
`pi/4`
`pi/2`
`pi`

ANSWER :B
6921.

Consider an ellipse (x^(2))/(13)+(y^(2))/(4)=1 and a variaote point P(1-,2t) is takne in such a way that angle S_(1)PS_(2) is maximum where S_(1) and S_(2) are the foci of the given ellipse then the value of (S_(1)P)/(S_(2)P) is

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`(SQRT(2))/(sqrt(3))`
`(1)/(sqrt(5))`
`(1)/(sqrt(3))`
`(1)/(sqrt(2))`

ANSWER :C
6922.

When a pair of six faced fair dice are thrown, the probability that the sum of the numbers on the two dice is greater that 7, is

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`(1)/(3)`
`(5)/(12)`
`(1)/(2)`
`(1)/(4)`

Answer :B
6923.

Length of median from A to BC of triangle ABC where A (2,5) B (7,-1) and C (3,5) is

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`2SQRT3`
6
`3sqrt2`
`SQRT(20)`

ANSWER :D
6924.

The two geometric means between the numbers 1 and 64 are

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1 and 64
4 and 16
2 and 16
8 and 16

Answer :B
6925.

A fair die is rolled . Consider events E = {1, 3, 5} F = {2, 3} and G = {2, 3, 4, 5} . FindP(E//F) and P(F//E)

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Answer :(i) `(1)/(2), (1)/(3)`, (II) `(1)/(2), (2)/(3)` , (III) `(3)/(4), (1)/(4)`
6926.

Integrate the following functions x^2/sqrt(x^6+a^6)

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SOLUTION :Puttinng `x^3 = t`, we have
`DT = 3x^2 dx gt x^2 dx = 1/3 dt`
therefore` int x^2/sqrt(x^6+a^6) dx = int1/sqrt(t^2+(a^3)^2) 1/3 dt`
`=1/3 log|t+sqrt(t^2+(a^3)^2)|+c`
`=1/3 log|x^3+sqrt(x^6+a^6)|+c`
6927.

The points in the set {zinC: Arg " ((z-2)/(Z-6i))=pi/2}lie on the curve which is a (where C denotes the sets of all complex number )

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circle
pair of LINES
PARABOLA
HYPERBOLA

ANSWER :A
6928.

The solution of (dy)/(dx) = (x + 2y -3)/(2x + y -3) is

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`X + y + 2 = C (x-y)^(3)`
`x -y -2 = c (x-y)^(3)`
`x + y -2 = c (x-y)^(3)`
`x + y -2 = c (x + y)^(3)`

ANSWER :C
6929.

Find (dy)/(dx): x= te^(t),y=1 + log t

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ANSWER :`(1)/(t E^(t) (1 + t))`
6930.

Prove theA nn B = B nn A results of the sections 1.13 and 1.14 that are stated with our proof.

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SOLUTION :LET `X in A NN B ``:. A nnB =B nn A`
6931.

Evaluate : (i) int_(0)^(pi//2)xcosxdx (ii) int_(0)^(pi)cos2xlog sinx dx (iii) int_(1)^(2)(logx)/(x^(2))dx (iv) int_(0)^(pi//6)(2+3x^(2))cos3x dx

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Solution :`(i)` Integrating by PARTS, we get
` int_(0)^(pi//2)xcosxdx=[xsinx]_(0)^(pi//2)-int_(0)^(pi//2)1*sinxdx`
`=(pi)/(2)+[cosx]_(0)^(pi//2)=((pi)/(2)-1)`.
`(ii)` Integrating by parts, taking `log(sinx)` as the first function, we get
` int_(0)^(pi)cos2xlog sinx dx`
`=[(logsinx)*(sin2x)/(2)]_(0)^(pi)-int_(0)^(pi)(cotx*(sin2x)/(2))dx`
`=0-int_(0)^(pi)(cosx)/(sinx)*(2sinxcosx)/(2)dx=-int_(0)^(pi)COS^(2)XDX`
`=-(1)/(2)int_(0)^(pi)2cos^(2)xdx=-(1)/(2)int_(0)^(pi)(1+cos2x)dx`
`=-(1)/(2)*[x+(sin2x)/(2)]_(0)^(pi)=-(pi)/(2)`.
`(iii)` Integrating by parts, taking `(logx)` as the first function, we get
` int_(1)^(2)(logx)/(x^(2))dx=int_(1)^(2)(logx)*x^(-2)dx`
`=[(logx)(-(1)/(x))]_(1)^(2)-int_(1)^(2)(1)/(x)*(-(1)/(x))dx`
`=[-(log2)/(2)+(log1)/(1)]+int_(1)^(2)(dx)/(x^(2))`
`=(-log2)/(2)-[(1)/(x)]_(1)^(2)=(-log2)/(2)-{(1)/(2)-1}=((1-log2)/(2))`.
`(iv) int_(0)^(pi//6)(2+3x^(2))cos3x dx`
`=2int_(0)^(pi//6)cos3xdx+3int_(0)^(pi//6)x^(2)cos3xdx`
`=2[(sin3x)/(3)]_(0)^(pi//6)+3{[x^(2)((sin3x)/(3))]_(0)^(pi//6)-int_(0)^(pi//6)2x((sin3x)/(3))dx}` [integrating by parts]
`=(2)/(3)+(pi^(2))/(36)-2int_(0)^(pi//6)xsin3xdx`
`=(2)/(3)+(pi^(2))/(36)-2{[x((-cos3x)/(3))]_(0)^(pi//6)-int_(0)^(pi//6)1*((-cos3x)/(3))dx}` [integrating by parts]
`=(2)/(3)+(pi^(2))/(36)+(2)/(3)[xcos3x]_(0)^(pi//6)-(2)/(3)*[(sin3x)/(3)]_(0)^(pi//6)`
`=(2)/(3)+(pi^(2))/(36)-(2)/(9)((pi^(2))/(36)+(4)/(9))=(1)/(36)(pi^(2)+16)`.
6932.

The vertices of a triangle are (6, 0), (0, 6) and (6, 6). Then distance between its circumcentre and centroid, is

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`2sqrt(2)`
2
`SQRT(2)`
1

Answer :C
6933.

Origin is the orthocentre of DeltaABC where A = (5, -1), B = (-2, 3) then the orthocentre of DeltaOAC is

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(-4, -7)
(3, -2)
(-2, 3)
(5, -1)

ANSWER :C
6934.

I.F. Of the differential equation dy/dx+2y=e^(2x) is :

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`E^(2logx)`
2x
x
`x^2`

ANSWER :B
6935.

Find the probability of getting sum 7 when two dice are rolled

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ANSWER :`(1)/(6)`
6936.

If the points (1, 1, lambda) and (-3, 0, 1) be equidistant from the plane vecr.(3hati+4hatj-12hatk)+13=0 find the value of lambda.

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ANSWER :`lambda=1` OR `lambda=7/3`
6937.

Four bad apples are mixed with 20 good apples. If 2 apples are drawn at random at a time then find mean of number of bad apples

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ANSWER :`1//3`
6938.

Consider the inequalities x_(1)+x_(2)le3,2x_(1)+5x_(2)ge10x_(1),x_(2)ge0 which of the following point does not lie in the feasible region ?

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(2, 2)
(1, 2)
(2, 1)
(4, 2)

Solution :Since, the point (2, 1) does not satisfy the inequality
`2x_(1)+5x_(2)GE10`
Hence, option ( C ) is the CORRECT ANSWER.
6939.

Determine the intervals of concavity of the curve f(x)=(x-1)^(3)(x-5),x in Rand , points of inflection if any

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ANSWER :`x=1, x=3`
6940.

Evaluate the following integrals (iii) int_(0)^(pi/2) (1)/(4 +5 cos x) dx

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ANSWER :`1/3 LOG 2`
6941.

Evaluate the definite integral in exercise overset(1)underst(0) int (dx)/(1+x^(2))

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ANSWER :`(PI)/(4)`
6942.

If n= (sqrt2 +1)^6. Then the integer just greater than n is

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199
198
197
196

Answer :B
6943.

Evaluate the following integrals. intcosxcos2x cos3xdx

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ANSWER :`(1)/(4)[X+(sinx)/(2)+(sin4x)/(4)+(sin6x)/(6)]+C`
6944.

Solve graphically x le 0

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SOLUTION :
6945.

To prove geometrical properties of an ellipse, we may take its standard equation as (x^2)/(a^2)+(y^2)/(b^2)=1 we will assume that a gt bgt0and foci S,S' lie on positive and negative side of X-axis, respectively. If P is any point on the ellipse and G is same as above, then S'G"/"SG must be:

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<P>`(OS')/(OS)`
`(G'S)/(OG)`
`(S'P)/(SP)`
`(a)/(B)`

ANSWER :C
6946.

If the vertices of a Delta ABC are A = (2, 3, 5), B = (-1, 3, 2), C = (3,5, -2) then the area of the DeltaABC (in sq. units) is

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`6sqrt2`
`8 SQRT3`
`9sqrt2`
`8sqrt2`

ANSWER :C
6947.

Number of points lying on the line 7x+4y+2=0 which is equidistant from the lines 15x^2+56xy+48y^2=0 is

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0
1
2
4

Answer :C
6948.

For x,y in R define a relation R by x R y if and only if x-y +sqrt(2) is an irrational number .Then R is

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an EQUIVALENCE relation
SYMMETRIC
transitive
reflexive but not symmetric & transitive

ANSWER :D
6949.

Write the differential equation of parabolas y^2=8x+c

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SOLUTION :GIVEN EQUATION is `y^2=8x+c`rArr2ydy/dx=8rArrydy/dx=4` is the requaired DIFFERENTIAL equation.
6950.

A relation R={(x,y):x,y in A and x lt y} is defined on set A={1,2,3,4,5}. The relation R is :

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REFLEXIVE
symmetric
TRANSITIVE
equivalence

ANSWER :C