JEE 2023 — Mathematics PYQ
JEE | Mathematics | 2023Let A be the area of the region {(x,y):y≥x2,y≥(1−x)2,y≤2x(1−x)}. Then 540A is equal to ________.
Choose the correct answer:
- A.
25
(Correct Answer) - B.
24
- C.
23
- D.
22
25
Explanation
Solution
1. Curves ko pehchanen:
-
C1:y=x2 (Upward parabola)
-
C2:y=(1−x)2 (Upward parabola, vertex at x=1)
-
C3:y=2x(1−x)=2x−2x2 (Downward parabola)
2. Intersection points nikaalein:
-
C1 aur C2: x2=(1−x)2⟹x2=1+x2−2x⟹2x=1⟹x=21
-
C1 aur C3: x2=2x−2x2⟹3x2−2x=0⟹x(3x−2)=0⟹x=0,32
-
C2 aur C3: (1−x)2=2x−2x2⟹1+x2−2x=2x−2x2⟹3x2−4x+1=0
Solving this: (3x−1)(x−1)=0⟹x=31,1
3. Area (A) ki limit set karein:
Symmetry ke hisaab se, region x=31 se x=21 tak aur x=21 se x=32 tak bata hua hai. Dono parts barabar hain, isliye:
A=2∫1/31/2[yupper−ylower]dx
A=2∫1/31/2[2x(1−x)−(1−x)2]dx
A=2∫1/31/2[2x−2x2−(1+x2−2x)]dx
A=2∫1/31/2[−3x2+4x−1]dx
4. Integration karein:
A=2[−x3+2x2−x]1/31/2
Values put karne par:
A=2[(−81+42−21)−(−271+92−31)]
A=2[(−81)−(27−1+6−9)]
A=2[−81+274]=2[216−27+32]=2[2165]=1085
5. Final Value:
Hame 540A nikaalna hai:
540A=540×1085
540A=5×5=25
Jawab: 25

