Area Under Curves
The area bounded by the curves y=x,2y−x+3=0, and the x-axis in the first quadrant is:
Region bounded by curve and line
Select the correct option:
Solution
9
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Identify the boundaries: Curve 1: y=x (or x=y2). Curve 2: x=2y+3. Boundary 3: y=0 (x-axis).
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Find intersection points: Solve x=y2 and x=2y+3. y2=2y+3⟹y2−2y−3=0⟹(y−3)(y+1)=0. Since we are in the first quadrant (y>0), y=3. Intersection is at y=3,x=9. Point (9,3).
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Set up the integral with respect to y (Horizontal Strips): This avoids splitting the area. y goes from 0 to 3. Right boundary: line x=2y+3. Left boundary: curve x=y2. Area =∫03(xright−xleft)dy=∫03((2y+3)−y2)dy.
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Evaluate: =[y2+3y−y3/3]03 =(9+9−9)−0=9.
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About This Question
- Subject
- mathematics
- Chapter
- integral calculus
- Topic
- area under curves
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
9
-
Identify the boundaries: Curve 1: y=x (or x=y2). Curve 2: x=2y+3. Boundary 3: y=0 (x-axis).
-
Find intersection points: Solve x=y2 and x=2y+3. y2=2y+3⟹y2−2y−3=0⟹(y−3)(y+1)=0. Since we are in the first quadrant (y>0), y=3. Intersection is at y=3,x=9. Point (9,3).
-
Set up the integral with respect to y (Horizontal Strips): This avoids splitting the area. y goes from 0 to 3. Right boundary: line x=2y+3. Left boundary: curve x=y2. Area =∫03(xright−xleft)dy=∫03((2y+3)−y2)dy.
-
Evaluate: =[y2+3y−y3/3]03 =(9+9−9)−0=9.
This medium difficulty mathematics question is from the chapter integral calculus, covering the topic of area under curves. It appeared in the 2025 exam.
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