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 -1≤x≤2

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-30⇒y=10

Put y=10 in P1, we get 2(10)=5x2

⇒5x2=20⇒x=±2

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

Area=2∫02(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=5x2⇒x=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=22∫28x1/2dx-∫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):y≥x2,y≥(1-x)2,y≤2x(1-x)}. Then 540A is equal to ___________ .        [2023]



(25)

Region {(x,y):y≥x2,y≥(1-x)2,y≤2x(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=2∫1/31/2[2x-2x2-(1-x)2]dx

=2∫1/31/2(2x-2x2-1-x2+2x)dx

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

∴   540A=540×5108=25



Q 26 :

Let for x∈R, f(x)=x+|x|2 and g(x)={x,x<0x2,x≥0. 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,x≥00,x<0

g(x)={x2,x≥0x,x<0

fog(x)=f(g(x))={g(x),g(x)≥00,g(x)<0={x2,x≥00,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|,0≤x≤1} 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=2∫3-5212((x-x2)-(1-2x))dx

A=2∫3-5212(-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/4cosx dx+∫π/4πsinx dx+∫π5π/4-sinx dx+∫5π/43π/2-cosx dx

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+x2≤y≤3-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)

=2∫03(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=18⇒α3=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=0⇒f(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=1⇒f(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

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=2∫03[4-x2-(2-4-x2)]dx

=2∫03(24-x2-2)dx

=4∫03(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):1-2x≤y≤4-x2, x≥0, y≥0} is αβ, α,β∈ℕ, 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+y2≤8 and y2≤4x} is:     [2026]

  • π2+2

     

  • π2+13

     

  • π+23

     

  • π+4

     

(3)

A=∫022x dx+2∫128-4x2 dx

=83[x3/2]∫01+4∫122-x2 dx

=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):xy≤8, 1≤y≤x2, x≥0} 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)



Q 38 :

The area of smaller region bounded by the curve 9x2+4y2-36x+16y+16=0 and the line 3x+2y=8  is

  • 32(π+2)

     

  • 3(π-2)

     

  • 34(π-2)

     

  • 32(π-2)

     

(4)

π4ab-12ab

where a, b are length of semi minor and major axis.



Q 39 :

Let S be the region bounded by the curves y=x3 and y2=x. The curve y=2|x| divides S into two regions of areas R1 and R2. If max{R1,R2}=R2,then R2R1=



(19)

=∫01xdx-34

=[2x3/23-x44]10=512

R1=∫01/4(x-2x)dx

=[2x3/23-x2]01/4=148

∴ R2=1948

So, R2R1=19



Q 40 :

The area of the region bounded by the curve x=2y+3 and the lines y=1, y=-1 is:

  • 4 sq. units

     

  • 32 sq. units

     

  • 6 sq. units

     

  • 8 sq. units

     

(3)

Ans.      6 sq. units

Explanation :

Required area, A=∫-11(2y+3) dy

                             =[2y22+3y]-11

                              =[y2+3y]-11

                              =(1+3)-(1-3)

                              =4-(-2)

                              =6 sq. units.



Q 41 :

The area of the region bounded by the curves y=|x-2|, x=1, x=3 and the X-axis is:

  • 4 sq. units

     

  • 2 sq. units

     

  • 3 sq. units

     

  • 1 sq. unit

     

(4)

Ans.       1 sq. unit

Explanation:

Required area, A=∫13|x-2| dx

                             =∫12(2-x) dx+∫23(x-2) dx

                              =[2x-x22]12+[x22-2x]23

                               =12+12=1 sq. unit.



Q 42 :

The area bounded by the curve y=x, X-axis and ordinates x=-1 to x=2 is:

  • 0

     

  • 12 sq. unit

     

  • 32 sq. units

     

  • 52 sq. units

     

(4)

Ans.       52 sq. units

Explanation :

Bounded area,  =|∫-10x dx|+|∫02x dx|

=|-12|+|2|=12+2=52 sq. units.



Q 43 :

The area of the region bounded by the line 2y+x=8, X-axis and the lines x=2 and x=4 is:

  • 5 sq. units

     

  • 7 sq. units

     

  • 9 sq. units

     

  • 10 sq. units

     

(1)

Ans.        5 sq. units

Explanation:

Required area = Area of the shaded region

      =∫x=24y dx

      =∫2412(8-x) dx

       =12[8x-x22]24

       =12[(8·(4)-422)-(8·(2)-222)]

       =5 sq. unit.



Q 44 :

The area of the region bounded by the curve y=x+1 and the lines x=2, x=3 is:

  • 72 sq. units

     

  • 92 sq. units

     

  • 112 sq. units

     

  • 132 sq. units

     

(1)

Ans.         72 sq. units

Explanation :

Required area,  A=∫23(x+1) dx=[x22+x]23

                             =[92+3-42-2]

                             =[52+1]=72 sq. units.



Q 45 :

Area of the region in the first quadrant enclosed by the X-axis, the line y=x and the circle x2+y2=32 is: 

  • 16π sq. units

     

  • 4π sq. units

     

  • 32π sq. units

     

  • 24π sq. units

     

(2)

Ans.       4π  sq. units

Explanation:

We have, area enclosed by X-axis i.e., y=0, y=x and the circle x2+y2=32 in first quadrant.

Since,         x2+(x)2=32             [∵ y=x]

⇒                      2x2=32

⇒                           x=±4

So, the intersection point of circle x2+y2=32 and line y=x are (4, 4) or (-4,-4).

and                 x2+y2=(42)2

Since,                       y=0

∴               x2+(0)2=32

⇒                            x=±42

So, the circle intersects the X-axis at (±42,0).

Area of shaded region

=∫04x dx+∫442(42)2-x2 dx

=|x22|04+[x2(42)2-x2+(42)22sin-1(x42)]442

=162+[422·0+16sin-1(4242)-42(42)2-16-16sin-1(442)]

=8+[16·π2-216-16·π4]

=8+[8π-8-4π]=4π sq. units.



Q 46 :

The area of the region bounded by the curve y=16-x2 and X-axis is: 

  • 8π sq. units

     

  • 20π sq. units

     

  • 16π sq. units

     

  • 256π sq. units

     

(1)

Ans.         8π sq. units

Explanation:

Given equation of curve is y=16-x2 and the equation of line is X-axis i.e., y=0.

∴         16-x2=0                ...(i)

⇒             16-x2=0

⇒                      x2=16⇒x=±4

So, the intersection points are (4, 0) and (-4,0).

Therefore, area of the curve,

   A=∫-4416-x2 dx

       =∫-4442-x2 dx

        =[x242-x2+422sin-1(x4)]-44

        =[4242-42+8sin-1(44)]-[-4242-(-4)2+8sin-1(-44)]

         =[2·0+8·π2-0+8·π2]=8π sq. units.



Q 47 :

The area of the region bounded by the circle x2+y2=1 is: 

  • 2π sq. units

     

  • π sq. units

     

  • 3π sq. units

     

  • 4π sq. units

     

(2)

Ans.       π sq. units

Explanation:

We have,   x2+y2=12    [∵ r=±1]

⇒                     y2=1-x2

⇒                       y=1-x2

Therefore, area enclosed by the circle,

         =2∫-1112-x2 dx                [∵ ∫-aaf(x) dx=2∫0af(x) dx]

         =2·2∫0112-x2 dx

         =2·2[x212-x2+122sin-1(x1)]01

          =4[12·0+12·π2-0-12·0]

          =4·π4=π sq. units.



Q 48 :

Area lying in the first quadrant and bounded by the circle x2+y2=4 and the lines x=0 and x=2 is:

  • π sq. units

     

  • π2 sq. units

     

  • π3 sq. units

     

  • π4 sq. units

     

(1)

Ans.         π sq. units

Explanation:

The area bounded by the circle and the lines, x=0 and x=2, in the first quadrant is represented as shaded region.

Area OAB=∫02y dx

                     =∫024-x2 dx

                     =[x24-x2+42sin-1(x2)]02

                     =2(π2)=π



Q 49 :

The area of smaller part between the circle x2+y2=4 and the line x=1 is:

  • 4π3-3 sq. units

     

  • 8π3-3 sq. units

     

  • 4π3+3 sq. units

     

  • 5π3+3 sq. units

     

(1)

Ans.            4π3-3 sq. units

Explanation :

Area of smaller part=2∫124-x2 dx

=2[x24-x2+2sin-1(x2)]12

=2[2·π2-(32+2·π6)]

=2[π-(32+π3)]=4π3-3 sq. units.



Q 50 :

The area enclosed by the circle x2+y2=2 is equal to:

  • 4π sq. units

     

  • 22π sq. units

     

  • 4π2 sq. units

     

  • 2π sq. units

     

(4)

Ans.         2π sq. units

Explanation :

∵      Area=4∫022-x2 dx

                     =4[x22-x2+sin-1(x2)]02

                      =4[0+π2]

                      =2π sq. units.