Comprehension

Consider the following for the two (02) items that follow:
Let the curve f(x) = |x - 3|

What is the area bounded by the curve f(x) and y = 3?

This question was previously asked in
NDA-I (Mathematics) Official Paper (Held On: 13 Apr, 2025)
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  1. 3 square units
  2. 4-5 square units
  3. 7-5 square units
  4. 9 square units

Answer (Detailed Solution Below)

Option 4 : 9 square units
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Detailed Solution

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Calculation:

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Given,

The function is f(x) = |x - 3| , and we need to find the area bounded by the curve and the line y = 3.

To find the points of intersection, we set the function equal to 3:

\( |x - 3| = 3 \)

Solving for x :

- For\( x \geq 3 \), \(x - 3 = 3 \), which gives x = 6 .
- For ( x < 3 ), 3 - x = 3 , which gives x = 0 .

Therefore, the points of intersection are x = 0  and x = 6 .

The area can be calculated by integrating the difference between the curve and the line from x = 0 to x = 6. The integral is split into two parts due to the absolute value function:

\( A = \int_{0}^{3} (3 - x) \, dx + \int_{3}^{6} (x - 3) \, dx \)

For x in [0, 3] , ( f(x) = 3 - x ), and for ( x in [3, 6] ), ( f(x) = x - 3 ).

Compute both integrals:

- For x in [0, 3] :

\( \int_{0}^{3} (3 - x) \, dx = \left[ 3x - \frac{x^2}{2} \right]_{0}^{3} = 9 - 4.5 = 4.5 \)

- For x in [3, 6] :

\( \int_{3}^{6} (x - 3) \, dx = \left[ \frac{x^2}{2} - 3x \right]_{3}^{6} = 4.5 \)

Step 4: The total area is the sum of the two areas:

\( A = 4.5 + 4.5 = 9 \, \text{square units} \)

∴ The total area bounded by the curve and the line is 9 square units.

The correct answer is Option (4):

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