The area of the region bounded by the curve \( x^2=4y \) , the line \( x=4y-2 \) and x-axis is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( \displaystyle\frac{5}{24} \) Square units
Points where the boundaries meet:
\( \displaystyle \text{curve and x-axis: } (0,0) \)
\( \displaystyle \text{line and x-axis: } (-2,0) \)
Curve and line: \( y=\frac{x+2}{4} \), so
\( \displaystyle x^2=x+2\ \Rightarrow\ (x-2)(x+1)=0 \)
\( \displaystyle x=-1\ \text{or}\ x=2 \)
The region with all three as boundaries has corners (−2, 0), (−1, 1/4) and (0, 0). Its upper boundary is the line from x = −2 to x = −1 and the parabola from x = −1 to x = 0, with the x-axis below:
\( \displaystyle \text{Area}=\int_{-2}^{-1}\frac{x+2}{4}\,dx+\int_{-1}^{0}\frac{x^2}{4}\,dx \)
\( \displaystyle =\left[\frac{(x+2)^2}{8}\right]_{-2}^{-1}+\left[\frac{x^3}{12}\right]_{-1}^{0} \)
\( \displaystyle =\frac{1}{8}+\frac{1}{12} \)
\( \displaystyle =\frac{5}{24} \)
The area is \( \frac{5}{24} \) square units.
Why the other options are incorrect
Option (1) \( \displaystyle\frac{9}{8} \) Square units — Incorrect. \( \frac{9}{8} \) is the area enclosed between the line and the parabola alone, from x = −1 to x = 2; that region is not bounded by the x-axis.
Option (2) \( \displaystyle\frac{9}{24} \) Square units — Incorrect. The area is \( \frac{1}{8}+\frac{1}{12}=\frac{5}{24} \), not \( \frac{9}{24} \).
Option (4) \( \displaystyle\frac{11}{24} \) Square units — Incorrect. The area is \( \frac{5}{24} \), not \( \frac{11}{24} \).