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7251.

Find the equation of the circle passing through the intersection of the circles x^2 + y^2 = 2ax and x^2 + y^2 = byand having its center on the line x/a - y/b = 2.

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ANSWER :`RARR x^2 + y^2 - 3AX + by = 0`
7252.

Examine whether the function f given by f(x)= x^2 is continuous at x= 0.

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ANSWER :HENCE, F is CONTINUOUS at x=0.
7253.

A group of students and teachers takes a field trip, such that the student to teacher ratio is 8 to 1. The total number of people on the field trip is between 60 and 70. {:("Quantity A","Quantity B"),("The number of teachers on the field trip",6):}

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ANSWER :QUANTITY A is GREATER.
7254.

Let |(x,2,x),(x^(2),x,6),(x,x,6)|=Ax^(4)+Bx^(3)+Cx^(2)+Dx+E. Then the value of 5A+4B+3C+2D+E is equal to

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zero
`-16`
16
`-11`

Solution :LET the given DETERMINANT be equal to `Delta(x)`. Then,
`5A+4B+3C+2D+E=Delta(1)+Delta'(1)`
Now, `Delta(1)=0` as `R_(2) and R_(3)` are IDENTICAL.
`Delta'(x)=|(1,0,1),(x^(2),x,6),(x,x,6)|+|(x,2,x),(2x,1,0),(x,x,6)|+|(x,2,x),(x^(2),x,6),(1,1,0)|`
`Delta'(1)=|(1,2,1),(2,1,0),(1,1,6)|+|(1,2,1),(1,1,6),(1,1,0)|`
`=-17+(12+1-1-6)=-11`
7255.

If the third term in the expansion of (x + x log_10 x)^5 is 10^6 then x is

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1
100
`(1)/(SQRT10)`
10

Answer :D
7256.

A sequence a _(0) , a_(1), a _(2), a_(3)………..a _(n) …. is defined such that a _(0) =a _(1) =a and a _(n-1) = ( a _(n-1) a _(n)) + 1for n ge 1. Which of the following is true ?

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ANSWER :`4A _( 2004)`
7257.

int (sin x cos x)/(1 +cos^(4) x )dx =

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`(1)/(2) cot^(-1) (COS^(2)x)+ c`
`(1)/(2) TAN^(-1) (cos^(2)x ) + C `
`2 cot^(-1) (cos^(2) x ) + C `
`2 tan^(-1) (cos^(2) x )+ C `

ANSWER :A
7258.

What is the solution set to the equation2/(7-m)=4/m-(5-m)/(7-m)?

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{4,7}
{4,5}
{1,7}
{4}

ANSWER :D
7259.

Statement-I :If x_n=cos(pi//2^n)+isin (pi//2^n) then x_1.x_2.x_3…..=-1Statement-II : x_n=cos(pi//4^n)+isin(pi//4^n) then x_1.x_2.x_3…..infty=-1

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Only I is true
Only II is true
Both I and II are true
Neither I nor II are true

Answer :A
7260.

Consider the two complex numbers z and w, such that w=(z-1)/(z+2)=a+ib, " where " a,b in R " and " i=sqrt(-1). Which of the following is the value of -(b)/(a), whenever it exists?

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`3tan(theta/2)`
`1/3tan(theta/2)`
`-(1)/(3)cot theta`
`3cot""theta/2`

Answer :D
7261.

Consider the two complex numbers z and w, such that w=(z-1)/(z+2)=a+ib, " where " a,b in R " and " i=sqrt(-1). Which of the following equals to abs(z)?

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`ABS(W)`
`(a+1)^(2)+B^(2)`
`a^(2)+(b+2)^(2)`
`(a+1)^(2)+(b+1)^(2)`

ANSWER :B
7262.

If f'(x)=x^(2)+5 and f(0)=-1 then f(x)=...

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`X^(3)+5x-1`
`x^(3)+5x+1`
`(1)/(3)x^(3)+5x-1`
`(1)/(3)x^(3)+5x+1`

ANSWER :C
7263.

Chord of constanct of tangent to (x^(2))/(a^(2))+(y^(2))/(b^(2))=1 from any point on its director circle insterset the director circle at C and D. Find the locus of point of intersection of tangents of the circle at C and D.

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ANSWER :`(a^(2)+B^(2))^(3)`
7264.

Evaluate the following integrals int x cot^(2) x dx

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Answer :`log|sinx|-X cot x - (1)/(2) x^(2) + C`
7265.

There are four balls of different colours and four boxes of colours same as of the balls the number of ways in which the balls, one in each box, could be placed such that a ball does not go to a box of its own colour is

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`5/8`
`3/8`
`1/8`
`7/8`

ANSWER :B
7266.

IF a_0,a_1….,a_11 are the arithmetic progression with common difference d, then their mean deviation from their arithmetic mean is

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`30/11|d|`
`2|d|`
`3|d|`
`12|d|`

ANSWER :C
7267.

Let A,B, C be three mutually independent events. Consider the two statements S_(1)and S_(2). {:(S_(1):A and B nnC "are independent.",),(S_(2):A and B nnC "are independent.",):} Then

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<P>both `S_(1) and S_(2)` are true
only `S_(1)` is true
only `S_(2)` is true
NEITHER `S_(1)` nor `S_(2)` is true

Solution :We are given that
`P(AnnB)=P(A)P(B)`
`P(BnnC)=P(B)P(C)`
`P(CnnA)=P(C)P(A)`
`P(AnnBnnC)=P(A)(B)P(C)`
We have, `P(Avv(BnnC)=P(A)(B)P(C)=P(A)P(B)P(C)=P(A)P(BnnC)`
`impliesA and BnnC` are independent
Therefore, `S_(2)` is true. Also,
`P[(Ann(BUUC)]=P[(AnnB)uu(AnnB)nn(AnnC)]`
`=P(AnnB)+P(AnnC)-P(AnnBnnC)`
`=P(A)P(B)+P(A)P(C)-P(A)P(B)P(C)`
`P(A)[P(B)+P(C)-P(B)P(C)]`
`P(A)[P(B)+P(C)-P(BnnC)]`
`=P(A)P(BnnC)`
7268.

Let R = {(3,1),(1,3),(3,3) } be a relation defined on the set A = {1,2,3}. Then , R is symmetric , transitive but not reflexive.

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SOLUTION :N/A
7269.

int sin^(2) x cos^(2) x dx =

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`(1)/(2)( x -(sin 4x)/(4)) + c `
`(1)/(8)( x -(sin 4x)/(4)) + c `
`(1)/(8)( x +(sin 4x)/(4)) + c `
`(1)/(2)( x +(sin 4x)/(4)) + c `

ANSWER :B
7270.

Let (dy)/(dx) + y = f(x) where y is a continuous function of x with y(0) = 1 and f(x) = {{:(e^(-x), if o le x le 2),(e^(-2),if x gt 2):} Which of the following hold(s) good ?

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`y(1) = 2e^(-1)`
`y'(1) = -e^(-1)`
`y(3) = -2e^(-3)`
`y'(3) = -2e^(-3)`

Solution :`(dy)/(dx)+y = f(x)` is linear differential equation.
`I.F. = e^(x)`
`therefore"""Solution is ye"^(x) = INT e^(x) f(x) dx + C`
now if `0 LE x le 2` then `ye^(x) = int e^(x) e^(-x) dx + C`
`rArr""ye^(x) = x + C`
`y(0) = 1, rArr C = 1`
`therefore""ye^(x) = x + 1`
`therefore""y=(x+1)/(e^(x))`,
`therefore""y(1) = (2)/(e)`
Also y' = `y'=(e^(x)-(x+1)e^(x))/(e^(2x))`
`rArr""y'(1) = (e-2e)/(e^(2))=(-e)/(e^(2))=-(1)/(e)`
If x `gt` 2
`ye^(x) = int e^(x-2) dx`
`therefore""ye^(x) = e^(x-2) + C`
`therefore""y = e^(-2) + Ce^(-x)`
As y is continuous
`therefore""underset(x rarr 2)("lim")(x+1)/(e^(x))=underset(x rarr 2)("lim")(e^(-2)+ Ce^(-x))`
`therefore""3e^(-2) = e^(-2) + Ce^(-2) rArr C = 2`
`therefore"""for x" gt 2`
`y=e^(-2) + 2e^(-x)`
`rArr""y(3) = 2e^(-3)+e^(-2) = e^(-2) (2e^(-1)+1)`
`rArr""y'= -2e^(-x)`
`rArr""y'(3) = - 2e^(-3)`
7271.

Using differentials, find the approximate value ofeach of the following: (a)(17/81)^(1/4)""(b) (33)^(-1/5)

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Solution :(a) Let `f(x)=x^(1/4)rArrf'(x) = 1/4 x ^((-3)/4)`
Now, let`x = 16/81andDelta x = 1/81`
`:.f(x+Delta x)~= f(x)+Delta xf'(x)`
` RARR(x+Delta x)^(1/4) ~= x^(1/4 + 1/(4x^(3/4)) xx Delta x`
`rArr(16/81+1/81)^(1/4) ~=(16/81)^(1/4)+(1/81)/(4(16/81)^(3/4))`
`rArr (17/81)^(1/4) ~= 2/3 + 1/(81 xx 4 (2/3)^(3))`
`=2/3 + 1/96 = 65/96`
`rArr(17/81)^(1/4) ~=0.677`
(b) Let` f(x)=x^(-1/5) rArr f'(x)=(-1)/5 x ^(-6)/5)`
Now, let x = 32AND`Delta x = 1`
` :.f(x+Delta x) ~= f(x) + Delta x f'(x)`
` rArr(x+ Delta x)^(-1//5) ~= x ^(-1//5) - 1/(5X^(6/5)) Delta x`
`(33)^(-1/5) ~= (32)^((-1)/5) - 1/(5(32)^(6/5))`
`= 1/2 - 1/(5 xx 2^(6)) = 0.5 - 1/320`
` = 0.5 - 0.003`
` rArr (33)^(-1/5) ~= 0.497`
7272.

Let f(z) is of the form alpha z +beta , wherealpha, beta,z are complex numbers such that |alpha| ne |beta|.f(z) satisfies followingproperties : (i)If imaginary part of z is non zero, then f(z)+bar(f(z)) = f(barz)+bar(f(z)) (ii)If real part of of z is zero , then f(z)+bar(f(z)) =0 (iii)If z is real , then bar(f(z)) f(z) gt (z+1)^2 AA z in R (4x^2)/((f(1)-f(-1))^2)+y^2/((f(0))^2)=1 , x , y in R, in (x,y) plane will represent :

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HYPERBOLA
CIRCLE
ellipse
pair of line

Answer :A
7273.

Let f(x) is of the form alpha z _beta , where alpha, beta are constants and alpha, beta,z are complex numbers such that |alpha| ne |beta|.f(x) satisfies followingproperties : (i)If imaginary part of z is non zero, then f(x)+bar(f(z)) = f(barz)+bar(f(z)) (ii)If real part of of z is zero , then f(z)+bar(f(x)) =0 (iii)If z is real , then bar(f(x)) f(x) gt (x+1)^2 AA z in R Consider ellipse S:x^2/((Re(alpha))^2) + y^2/(Im(beta))^2) =1 , x, y in R in (x,y) plane , then point (1,1) will lie :

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OUTSIDE the ELLIPSE S
INSIDE the ellipse S
on the ellipse S
none of these

Answer :B
7274.

Assertion (A) : Orthocentre of the triangle formed by any three tangents to the parabola lies on the directrix of the parabola Reason ® : The orthocentre of the triangle formed by the tangents at t_1, t_2 ,t_3 to the parabola y^(2) =4ax is (-a ( t_1+t_2+t_3+t_1t_2t_3) )

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Both A and R are true and R `RARR A `
Both A and R are true and` R CANCEL rArr A `
A is true but R is false
A is false but R is true.

ANSWER :A
7275.

Express the matrix B=[{:(2,-2,-4),(-1,3,4),(1,-2,-3):}]as the sum of a symmetric and a skew symmetric matrix.

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Answer :`[{:(2,-(3)/(2),-(3)/(2)),(-(3)/(2),3,1),(-(3)/(2),1,3):}]+[{:(0,-(1)/(2),-(5)/(2)),((1)/(2),0,3),((3)/(2),-3,0):}]`
7276.

The shortest distance between the straight line passing through the point A = (6, 2,2) and parallel to the vector (1,-2,2) and the straight line passing through A (-4, 0, -1) and parallel to the vector (3,-2,-2) is

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9
8
5
2

Answer :A
7277.

Find the number of garlands that can be made using 6 different coloured flowers taken 4 at a time

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ANSWER :45
7278.

If the line joining the points A (1, 0, 0) andB(0, 0, 1) is a normal to the plane (pi)which passes through the point A, them the angle between the planes (pi) and x+y+z=6 is

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`(PI)/(6)`
`(pi)/(4)`
`(pi)/(3)`
`(pi)/(2)`

ANSWER :A
7279.

If 1, 2, 3 and 4 are the roots of the equation x^(4)+ax^(3)+bx^(2)+cx+d=0 , then a+2b+c is equal to

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-25
0
10
24

Answer :C
7280.

The value of cosec 20^(@).cosec40^(@).cosec60^(@).cosec80^(@) is

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`3//16`
`16//3`
`5//16`
`16//5`

ANSWER :B
7281.

If the 4th, 10th and 16th terms of a G.P. are x,y and z respectively,then x,y,z are in

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G.P.
A.P.
H.P.
A.G.P.

Answer :A
7282.

Find the coordinates of the point where the line through the points A (3, 4, 1) and B (5, 1, 6) crosses the XY-plane.

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ANSWER :`((13)/(5),(23)/(5),0)`
7283.

A car accelerates from rest at a constant rate of 2 m//s^(2) and comes to rest. If it remains in motion for 3 seconds, then the maximum speed attained by the car is :

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2 m/s
3 m/s
4 m/s
6 m/s

Answer :A
7284.

The value of m for which straight line 3x-2y+z+3=0=4x-3y+4z+1 is parallel to the plane 2x-y+mz-2=0 is ___

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`-2`
8
-18
11

Answer :A
7285.

A factory produces lazor blades and 1 in 500 blades is estimated to be defective. The blades are supplied in packetsof 10. IN a consignment of 10,000 packets, using poisson distribution, find approximately the number of packets which contain no defective blades. (Given e^(-0.02) = 0.9802)

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ANSWER :9802
7286.

At what point, the slope of the curve y=-x^(3)+3x^(2)+9x-27 is maximum ? Also find the maximum slope.

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ANSWER :`=-16`
7287.

Find the value of a so that the points (1,4),(2,7),(3,a) are collinear.

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SOLUTION :As the point (1,4),(2,7),(3,a) are COLLINEAR we have the area of the TRIANGLE with vertices (1,4),(2,7),(3,a) is zero.
`THEREFORE` `1/2{1(7-a)+2(a-4)+3(4-7)}=0`
or, 7-a+2a-8+12-21=0.
`implies` a=10.
7288.

Resolve (2x^(3)+3x^(2)+5x+7)/((x+1)^(5)) into partial fractions.

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ANSWER :`:. (2x^(3)+3X^(2)+5x+7)/((x+1)^(5)) = - (2)/((x+1)^(2)) - (3)/((x+1))+(5)/((x+1)^(4)) + (3)/((x+1)^(5))`
7289.

If the foot of perpendicular drawn from the point (1, 0, 3) on a line passing through ( alpha, 7, 1) is((5)/(3), (7)/(3), (17)/(3)), then alpha is equal to …………

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3
6
5
4

Answer :D
7290.

Evaluate the following integrals : (i) int(1)/((x+1)sqrt(2x-3))dx (ii) int(1)/((x+1)sqrt(x^(2)+x-1))dx (iii) int(1)/((x^(2)+3x+3)sqrt(x+1))dx (iv) int(1)/((x^(2)-3x+2)sqrt(x^(2)-2))dx

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Solution :`(i)` We have,
`int(1)/((x+1)sqrt(2x-3))dx`
Let us put `2x-3=t^(2)` so that `dx=tdt` and `x=(t^(2)+3)/(2)impliesx+1=(t^(2)+5)/(2)`
`=int(tdt)/((t^(2)+5)/(2).t)=2int(1)/(t^(2)+5)dt=(2)/(sqrt(5))tan^(-1)((t)/(sqrt(5)))+C`
`==(2)/(sqrt(5))tan^(-1)((sqrt(2x-3))/(sqrt(5)))+C`
`(ii)` We have,
`(1)/((x+1)sqrt(x^(2)+x-1))dx`
Let us put `(1)/(x+1)=t` so that `x=(1)/(t)-1` and `dx=-(1)/(t^(2))dt`
`=int(t)/(sqrt((1)/(t^(2))-(2)/(t)+1+(1)/(t)-1-1))xx-(1)/(t^(2))dt`
`=-int(1)/(sqrt(1-t-t^(2)))dt=-int(1)/(sqrt((5)/(4)-(t+(1)/(2))^(2)))dt`
`=cos^(-1)((t+(1)/(2))/((sqrt(5))/(2)))+C`
`=cos^(-1)((2T+1)/(sqrt(5)))+C=cos^(-1)((x+3)/(sqrt(5)(x+1)))+C`
`(iii) int(1)/((x^(2)+3x+3)sqrt(x+1))dx`
Let us put `x+1=t^(2)` so that `dx=2tdt` and
`x^(2)+3x+3=(t^(2)-1)^(2)+3(t^(2)-1)+3`
`=t^(4)-2t^(2)+1+3t^(2)-3+3`
`=t^(4)+t^(2)+1`
`=int(1)/((t^(4)+t^(2)+1)*t)*2tdt`
`=int(2)/(t^(4)+t^(2)+1)dt=int((2)/(t^(2)))/(t^(2)+(1)/(t^(2))+1)dt`
`=int((1+(1)/(t^(2)))-(1-(1)/(t^(2))))/(t^(2)+(1)/(t^(2))+1)`
`=int(1+(1)/(t^(2)))/((t-(1)/(t))^(2)+3)dt-int(1-(1)/(t^(2)))/((t+(1)/(t))^(2)-1)dt`
`=int(d(t-(1)/(t)))/((t-(1)/(t))^(2)+3)-int(d(t+(1)/(t)))/((t+(1)/(t))^(2)-1)dt`
`=(1)/(sqrt(3))tan^(-1)((t-(1)/(t))/(sqrt(3)))-(1)/(2)ln|(t+(1)/(t)-1)/(t+(1)/(t)+1)|+C`
`=(1)/(sqrt(3))tan^(-1)((x)/(sqrt(3(x+1))))-(1)/(2)ln|((x+2)-sqrt(x+1))/((x+2)+sqrt(x+1))|+C`, where `C` is a constant of INTEGRATION.
`(iv)` We have,
`int(1)/((x^(2)-3x+2)sqrt(x^(2)-2))dx=int(1)/((x-1)(x-2))*(1)/(sqrt(x^(2)-2))dx`
`=int((1)/(x-2)-(1)/(x-1))(1)/(sqrt(x^(2)-2))dx`
`=int(1)/((x-2)sqrt(x^(2)-2))dx-int(1)/((x-1)sqrt(x^(2)-2))dx`
`=l_(1)-l_(2)`,SAY
Now `l_(1)=int(1)/((x-2)sqrt(x^(2)-2))dx`
`=int(txxt)/(sqrt(2t^(2)+4t+1))xx-(1)/(t^(2))dt` Let us put `x-2=(1)/(t)`
`=(-1)/(sqrt(2))int(1)/(sqrt(t^(2)+2t+(1)/(2)))dt` `dx=-(1)/(t^(2))dt`
`=(-1)/(sqrt(2))int(1)/(sqrt((t+1)^(2)-(1)/(2)))dt` `x=(1)/(t)+2=(1+2t)/(t)`
`=-(1)/(sqrt(2))ln|(t+1)+sqrt(t^(2)+2t+(1)/(2))|+C_(1)` `x^(2)-2=(1+4t+4t^(2)-2t^(2))/(t^(2))`
`=-(1)/(sqrt(2))ln|(x-1)/(x-2)+(sqrt(x^(2)-2))/(sqrt(2)(x-2))|+C_(1)`,`C_(1)` is a constant of integration.
and `l_(2)=int(1)/((x-1)sqrt(x^(2)-2))dx`
Let us put `x-1=(1)/(u)`
`=int(uxxu)/(sqrt(1+2u-u^(2))xx-(1)/(u^(2))du` `dx=-(1)/(u^(2))du`
`=-int(1)/(sqrt(2-(u+1)^(2))du` `x^(2)-2=((1)/(u)+1)^(2)-2`
`=cos^(-1)((u-1)/(sqrt(2)))+C_(2)=cos^(-1)((x-2)/(sqrt(2)(x-1)))+C_(2)` `=(1+2u-u^(2))/(u^(2))`
Hence, `l=int(1)/((x^(2)-3x+2)sqrt((x^(2)-2)))dx=-(1)/(sqrt(2))ln|(x-1)/(x-2)+(sqrt(x^(2)-2)/(sqrt(2)(x-2))|-cos^(-1)((x-2)/(sqrt(2)(x-1)))+k` where `k` is a constant.
7291.

F: R to Rdefinedbyf (x)= (1)/(2x^2 +5)therangeof F is

Answer»

A. `(5,OO)`
B. `[0,1/5]`
C. `[1/5 ,5]`
D. noneof these

Answer :D
7292.

The probabilities of solving a problem by three students A,B,C independently are 1/3,1/4,1/5. The probability that the problems will be solved is………

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`(1)/(60)`
`(3)/(5)`
`(48)/(60)`
`(57)/(60)`

ANSWER :B
7293.

Find the scalar and vector projection of veca on vecb. veca = hati,vecb = hatj

Answer»

SOLUTION :Scalar PROJECTION of `VECA` on `vecb`
= `(veca.vecb)/|vecb| =(hati.hatj)/|hatj| = 0[becausehati.hatj = 0]`
VECTOR projection of `veca` on `vecb = VEC0`
7294.

From the two system of lines x - h = 0 where 0lehle5 and y - k = 0 where 0lekle3,how many squares can be formed.

Answer»

`

ANSWER :26
7295.

If A(3,4,5),B(4,6,3),C(-1,2,4) and D(-1,2,4) are suchthat the angle betweenthe lines DC and AB is theta, then costheta is equal is

Answer»

`7/9`
`2/9`
`4/9`
`5/9`

ANSWER :C
7296.

Determine whether or not each of the definition of ** given below gives a binary operation. In the even that ** is not a binary operation , give justification for this . On Z^(+) , define ** by a" * " b = a - b

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SOLUTION :N/A
7297.

Determine whether or not each of the definition of ** given below gives a binary operation. In the even that ** is not a binary operation , give justification for this . On Z^(+) , define **by a" * " b = ab

Answer»


SOLUTION :N/A
7298.

The modulus-amplitude form of ((1-i)^(3) (2-i))/((2+i) (1 +i)) is

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`2 CIS (pi "tan"^(-1) (4)/(3))`
`2 cis (-"tan"^(-1) (4)/(3))`
`2 cis (-pi + "tan"^(-1) (4)/(3))`
`2 cis ("tan"^(-1) (4)/(3))`

Answer :A
7299.

3. ^n C_0-8. ^n C_1 + 13. ^n C_1 - 18 , ^n C_3 + ….. (n+1) terms =

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0
`-1`
1
2

Answer :A
7300.

Find the centre and radius of each of the circles whose equations are given below. 3x^(2) + 3y^(2) - 5x - 6y + 4 =0

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ANSWER :` ((5)/( 6), 1) , ( SQRT(13))/(6) `