Class CBSE Class 12 Mathematics Applications of Integrals Q #1461
COMPETENCY BASED
REMEMBER
5 Marks 2025 AISSCE(Board Exam) LA
Draw a rough sketch for the curve $y=2+|x+1|$. Using integration, find the area of the region bounded by the curve $y=2+|x+1|$, $x=-4$, $x=3$ and $y=0$.

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Detailed Solution

Step 1: Sketching the Curve

The function is $y = 2 + |x+1|$. We know that $|x+1|$ is a V-shaped graph with the vertex at $x = -1$. Adding 2 shifts the graph upwards by 2 units. Therefore, the vertex of the given graph is at $(-1, 2)$.

Step 2: Defining the function piecewise

We can define the function as follows: $y = 2 + (x+1)$ for $x \ge -1$, which simplifies to $y = x + 3$. $y = 2 - (x+1)$ for $x < -1$, which simplifies to $y = -x + 1$.

Step 3: Setting up the integral

We need to find the area bounded by the curve, $x = -4$, $x = 3$, and $y = 0$. Since $y$ is always positive, the area is given by the integral of $y$ with respect to $x$ from $-4$ to $3$. We need to split the integral at $x = -1$ because the function is defined differently on either side of this point. Area $ = \int_{-4}^{3} (2 + |x+1|) dx = \int_{-4}^{-1} (-x + 1) dx + \int_{-1}^{3} (x + 3) dx$

Step 4: Evaluating the first integral

$\int_{-4}^{-1} (-x + 1) dx = [-\frac{x^2}{2} + x]_{-4}^{-1} = (-\frac{(-1)^2}{2} + (-1)) - (-\frac{(-4)^2}{2} + (-4)) = (-\frac{1}{2} - 1) - (-\frac{16}{2} - 4) = -\frac{3}{2} - (-8 - 4) = -\frac{3}{2} + 12 = \frac{21}{2}$

Step 5: Evaluating the second integral

$\int_{-1}^{3} (x + 3) dx = [\frac{x^2}{2} + 3x]_{-1}^{3} = (\frac{3^2}{2} + 3(3)) - (\frac{(-1)^2}{2} + 3(-1)) = (\frac{9}{2} + 9) - (\frac{1}{2} - 3) = \frac{27}{2} - (-\frac{5}{2}) = \frac{27}{2} + \frac{5}{2} = \frac{32}{2} = 16$

Step 6: Calculating the total area

Area $ = \frac{21}{2} + 16 = \frac{21}{2} + \frac{32}{2} = \frac{53}{2}$

Final Answer: $\frac{53}{2}$

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Pedagogical Audit
Bloom's Analysis: This is an REMEMBER question because the student needs to recall the properties of absolute value functions and the process of integration to find the area under the curve.
Knowledge Dimension: CONCEPTUAL
Justification: The question requires understanding the concept of absolute value functions, their graphical representation, and the application of integration to find the area under a curve.<\/span>
Syllabus Audit: In the context of CBSE Class 12, this is classified as Application of Integrals. The question involves sketching a curve and using integration to calculate the area, which aligns with the syllabus requirements for this topic.