Q 21 :

Let A be the area bounded by the curve y=x|x-3|, the x-axis and the ordinates x=-1 and x=2. Then 12A is equal to _____.          [2023]


 



(62)

y=x|x-3|=x(3-x),    when -1x2

Required area,  A=|-10(3x-x2)dx|+02(3x-x2)dx

=|[3x22-x33]-10|+[3x22-x33]02

=(32+13)+(122-83)

=116+103

Now 12A=12(116+103)=22+40=62



Q 22 :

If the area of the region bounded by the curves y2-2y=-x and x+y=0 is A, then 8A is equal to _________ .          [2023]



(36)

Required area =03[(2y-y2)-(-y)]dy

=03(3y-y2)dy

=[3y22-y33]03

=272-273=92sq. units

  8A=8×92=36



Q 23 :

If the area enclosed by the parabolas P1:2y=5x2 and P2:x2-y+6=0 is equal to the area enclosed by P1 and y=αx, α>0, then α3 is equal to _______ .        [2023]



(600)

Given, P1:2y=5x2,  P2:x2-y+6=0 and y=αx

The point of intersection of P1 and P2 is given by  

2y=5(y-6)2y=5y-30y=10

Put y=10 in P1, we get 2(10)=5x2

5x2=20x=±2

Thus P1 and P2 intersect at (-2,10) and (2,10).

Area=202(x2+6-5x22)dx=2[x33+6x-5x36]02

=2[(83+12-5×86)-0]=2(8)=16 sq. units

Now, the point of intersection of 2y=5x2 and y=αx, is given by

2αx=5x2x=2α5

Area=02α/5(αx-5x22)dx=[αx22-5x36]02α/5

=α2(4α225)-56(8α3125)=2α325-4α375=2α375

2α375=16  [Given]

α3=75×8=600



Q 24 :

Let α be the area of the larger region bounded by the curve y2=8x and the lines y=x and x=2, which lies in the first quadrant. Then the value of 3α is equal to _____ .    [2023]



(22)

We have y2=8x, y=x, x=2

The shaded region has the largest area. So, 

Area=28(22x-x)dx

α=2228x1/2dx-28xdx

=22×23[x3/2]28-[x22]28

=423[162-22]-12[64-4]=1123-30=223

Now 3α=22



Q 25 :

Let A be the area of the region {(x,y):yx2,y(1-x)2,y2x(1-x)}. Then 540A is equal to ___________ .        [2023]



(25)

Region {(x,y):yx2,y(1-x)2,y2x(1-x)}

y=x2                                       (i)

y=(1-x)2                              (ii)

y=2x(1-x)                           (iii)

Solving (ii) and (iii), we get

x=13 and x=1

  Required area  A=21/31/2[2x-2x2-(1-x)2]dx

=21/31/2(2x-2x2-1-x2+2x)dx

=21/31/2(-3x2+4x-1)dx=[-x3+2x2-x]1/31/2=5108

   540A=540×5108=25



Q 26 :

Let for xR, f(x)=x+|x|2 and g(x)={x,x<0x2,x0. Then area bounded by the curve y=(fog)(x) and the lines y=0, 2y-x=15 is equal to _______ .         [2023]



(72)

Here, f(x)=x+|x|2={x,x00,x<0

g(x)={x2,x0x,x<0

fog(x)=f(g(x))={g(x),g(x)00,g(x)<0={x2,x00,x<0

Required area =A1+A2

=03(x+152-x2)dx+12×152×15

=[x24+15x2-x33]03+2254=94+452-9+2254=2884=72



Q 27 :

Let the area of the region {(x,y):|2x-1|y|x2-x|,0x1} be A. Then (6A+11)2 is equal to __________.            [2023]



(125)

y|2x-1|,y|x2-x|

Both curves are symmetric about x=12

Hence 

A=23-5212((x-x2)-(1-2x))dx

A=23-5212(-x2+3x-1)dx=2[-x33+32x2-x]3-5212

=55-116

On solving,  6A+11=55,  (6A+11)2=125



Q 28 :

Let the area of the region bounded by the curve y=max{sinx, cosx}, lines x=0, x=3π2, and the x-axis be A. Then A+A2 is equal to ________ .        [2026]



(12)

A=0π/4cosxdx+π/4πsinxdx+π5π/4-sinxdx+5π/43π/2-cosxdx

A=(sinx)0π/4+(cosx)π/4π+(cosx)π5π/4+(sinx)5π/43π/2

A=12+12+1+1-12+1-12=3

A2+A=12



Q 29 :

The area of the region inside the ellipse  x2+4y2=4 and outside the region bounded by the curves y=|x|-1  and y=1-|x| is    [2026]

  • 3(π-1)

     

  • 2(π-1)

     

  • 2π-1

     

  • 2π-12

     

(2)

Required area=area of ellipse-shaded area

=π×2×1-4(12×1×1)=2π-2



Q 30 :

Let A1 be the bounded area enclosed by the curves y=x2+2, x+y=8 and y-axis that lies in the first quadrant. Let A2 be the bounded area enclosed by the curves y=x2+2, y2=x, x=2, and y-axis that lies in the first quadrant. Then A1-A2 is equal to            [2026]

  • 23(2+1)

     

  • 23(42+1)

     

  • 23(32+1)

     

  • 23(22+1)

     

(4)

A1=02((8-x)-(x2+2))dx

      =02(6-x-x2)dx

A1(6x-x22-x33)02=12-2-83=10-83=223

A2=02(x2+2)dx-23(22)

A2=(x33+2x)02-423

A2=83+4-423=203-423

A1-A2=23+423



Q 31 :

Let the line x=-1 divide the area of the region {(x,y):1+x2y3-x} in the ratio m:n, gcd(m,n)=1. Then m+n is equal to        [2026]

  • 26

     

  • 25

     

  • 28

     

  • 27

     

(4)

mn=-11[(3-x)-(1+x2)]dx-21[(3-x)-(1+x2)]dx=207

 m+n=20+7

=27



Q 32 :

Let P1:y=4x2  and  𝑃2:𝑦=𝑥2+27 be two parabolas. If the area of the bounded region enclosed between P1 and P2 is six times the area of the bounded region enclosed between the line y=αx, α>0 and P1, then α is equal to :   [2026]

  • 15

     

  • 12

     

  • 8

     

  • 6

     

(2)

Area bounded between P1 & P2 is

-33((x2+27)-(4x2))dx

                     (P.O.I. of P1 & P2 is x=±3)

=203(27-3x2)dx=2[27x-x3]03

=2[81-27]=108

 Area bounded between P1 & L is 18 sq. units

(Area between x2=4ay & line x=my is 8a23m3)

 Area between x2=y4 & x=yα is

8(116)23(1α)3=18

816·163α3=18α3=26·33

α=12



Q 33 :

Let f(α) denote the area of the region in the first quadrant bounded by x=0, x=1, y2=x and y=|αx-5|-|1-αx|+αx2. 

Then (f(0)+f(1)) is equal to     [2026]

  • 9

     

  • 12

     

  • 7

     

  • 14

     

(3)

at α=0f(0)

x=0, x=1, y2=x

y=|0·x-5|-|1-0·x|+0·x2

y=4

A1=01(4-x)dx

=4x-x3/23/2|01

=4-23(1)=103

at α=1f(1)

x=0, x=1, y2=x

y=|x-5|-|1-x|+x2, x(0,1)

y=5-x-(1-x)+x2

y=4+x2

[IMAGE 245]--------

A2=01[(4+x2)-x]dx

=4x+x33-x3232|01

=4+13-23=113

|f(0)+f(1)|=|A1+A2|=|103+113|=|213|=7

option (3)



Q 34 :

The area of the region enclosed between the circles x2+y2=4  and x2+(y-2)2=4 is: [2026]

  • 23(4π-33)

     

  • 43(2π-3)

     

  • 43(2π-33)

     

  • 23(2π-33)

     

(1)

A=203[4-x2-(2-4-x2)]dx

=203(24-x2-2)dx

=403(4-x2-1)dx

=4[12(x4-x2+4sin-1x2)-x]03

=4[12(3+4·π3)-3]=4[2π3-32]

=8π3-23  (Sq. units)



Q 35 :

If the area of the region {(x,y):1-2xy4-x2, x0, y0} is αβ, α,β, gcd(α,β)=1, then the value of (α+β) is:    [2026]

  • 91

     

  • 73

     

  • 85

     

  • 67

     

(2)

Required area=23×8-12×12×1

=163-14=6112=αβ

α+β=73



Q 36 :

The area of the region A={(x,y):4x2+y28 and y24x} is:     [2026]

  • π2+2

     

  • π2+13

     

  • π+23

     

  • π+4

     

(3)

A=022xdx+2128-4x2dx

=83[x3/2]01+4122-x2dx

=83+4×12[x2-x2+2sin-1(x2)]12

=83+2[2×π2-1-2×π4]

=83+2π-2-π

=π+23  sq. units



Q 37 :

The area of the region R={(x,y):xy8, 1yx2, x0} is   [2026]

  • 13(49loge(2)-15)

     

  • 23(20loge(2)+9)

     

  • 23(24loge(2)-7)

     

  • 13(40loge(2)+27)

     

(3)

A=12(x2-1)dx+28(8x-1)dx

A=8loge4-143=16loge2-143

=23(24loge2-7)