Area bounded by $y={{e}^{2x}}$ and lines x = 0, y = 0 and $x=\dfrac{e}{2}$ is given by
A. $\dfrac{1}{2}\int\limits_{0}^{2}{\ln ydy}$
B. $\dfrac{{{e}^{e}}-1}{2}$
C. ${{e}^{2}}$
D. None of these
Answer
683.1k+ views
Hint: First of all draw the area under the given curve to clearly visualize the question. Then, use $\int\limits_{a}^{b}{f(x)}={{e}^{2x}}$, a =0 and $b=\dfrac{e}{2}$.
Complete step-by-step answer:
Here we have to find the area bounded by $y={{e}^{2x}}$ and the lines x = 0, y = 0 and $x=\dfrac{e}{2}$. Before proceeding with the question, let us see how to find the area under a curve. Let the area be bounded by a curve, y = f(x), here the x-axis and the ordinates, x = a and x = b is given by $A=\int\limits_{a}^{b}{f(x)dx=\int\limits_{a}^{b}{ydx}}$.
Now, let us consider our question. Here let us first see the area under x = 0 and $x=\dfrac{e}{2}$ diagrammatically.
Basically, we have to find the shaded portion. So, we get the area as, \[A=\int\limits_{a}^{b}{f(x)dx}\]. By substituting$f(x)={{e}^{2x}}$, a = 0 and $b=\dfrac{e}{2}$ we get, \[A=\int\limits_{0}^{\dfrac{e}{2}}{{{e}^{2x}}dx}\]. We know that $\int\limits_{p}^{q}{{{e}^{ax}}}dx=\int\limits_{p}^{q}{\dfrac{{{e}^{ax}}}{a}}$. So we get, \[A=\int\limits_{0}^{\dfrac{e}{2}}{\dfrac{{{e}^{2x}}}{2}dx}\]
$A=\dfrac{1}{2}[{{e}^{2\left( \dfrac{e}{2} \right)}}-{{e}^{2\left( 0 \right)}}]$
$A=\dfrac{1}{2}\left( {{e}^{e}}-{{e}^{0}} \right)$
We know that ${{e}^{0}}=1$ so we get,
$A=\dfrac{1}{2}\left( {{e}^{e}}-1 \right)$
Hence, we get area between$y={{e}^{2x}}$, x = 0, y = 0 and $x=\dfrac{e}{2}$ as $\dfrac{1}{2}\left( {{e}^{e}}-1 \right)$ or $\dfrac{{{e}^{e}}-1}{2}$.
Therefore, option (B) is the correct answer.
Note: In this question, some students may make the mistake of taking ${{e}^{x}}$ instead of${{e}^{2x}}$, which is wrong, so the question must be read properly. Also, the students must note that the given formula is only for y = f(x) and that there is a slightly different formula for x = f(y). Also for y = f(x), we take vertical strips for the area under the curve while for x = f(y), we take horizontal strips for the area under the curve.
Complete step-by-step answer:
Here we have to find the area bounded by $y={{e}^{2x}}$ and the lines x = 0, y = 0 and $x=\dfrac{e}{2}$. Before proceeding with the question, let us see how to find the area under a curve. Let the area be bounded by a curve, y = f(x), here the x-axis and the ordinates, x = a and x = b is given by $A=\int\limits_{a}^{b}{f(x)dx=\int\limits_{a}^{b}{ydx}}$.
Now, let us consider our question. Here let us first see the area under x = 0 and $x=\dfrac{e}{2}$ diagrammatically.
Basically, we have to find the shaded portion. So, we get the area as, \[A=\int\limits_{a}^{b}{f(x)dx}\]. By substituting$f(x)={{e}^{2x}}$, a = 0 and $b=\dfrac{e}{2}$ we get, \[A=\int\limits_{0}^{\dfrac{e}{2}}{{{e}^{2x}}dx}\]. We know that $\int\limits_{p}^{q}{{{e}^{ax}}}dx=\int\limits_{p}^{q}{\dfrac{{{e}^{ax}}}{a}}$. So we get, \[A=\int\limits_{0}^{\dfrac{e}{2}}{\dfrac{{{e}^{2x}}}{2}dx}\]
$A=\dfrac{1}{2}[{{e}^{2\left( \dfrac{e}{2} \right)}}-{{e}^{2\left( 0 \right)}}]$
$A=\dfrac{1}{2}\left( {{e}^{e}}-{{e}^{0}} \right)$
We know that ${{e}^{0}}=1$ so we get,
$A=\dfrac{1}{2}\left( {{e}^{e}}-1 \right)$
Hence, we get area between$y={{e}^{2x}}$, x = 0, y = 0 and $x=\dfrac{e}{2}$ as $\dfrac{1}{2}\left( {{e}^{e}}-1 \right)$ or $\dfrac{{{e}^{e}}-1}{2}$.
Therefore, option (B) is the correct answer.
Note: In this question, some students may make the mistake of taking ${{e}^{x}}$ instead of${{e}^{2x}}$, which is wrong, so the question must be read properly. Also, the students must note that the given formula is only for y = f(x) and that there is a slightly different formula for x = f(y). Also for y = f(x), we take vertical strips for the area under the curve while for x = f(y), we take horizontal strips for the area under the curve.
Recently Updated Pages
Which of the following graphs shows the variation of class 12 physics CBSE

Draw a labelled diagram of the human male reproductive class 12 biology CBSE

Describe the experiment to compare the emf of two cells class 12 physics CBSE

What is standard hydrogen electrode

What is conventional current and electric current class 12 physics CBSE

2Bromopentane is treated with an alcoholic KOH solution class 12 chemistry CBSE

Trending doubts
Draw a labelled sketch of the human eye class 12 physics CBSE

Which are the Top 10 Largest Countries of the World?

Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE

Draw ray diagrams each showing i myopic eye and ii class 12 physics CBSE

Which is the correct genotypic ratio of mendel dihybrid class 12 biology CBSE

What is the Full Form of PVC, PET, HDPE, LDPE, PP and PS ?

