Question

The area bounded by the parabola $y ^ { 2 } = 4 a x$ its axis and two ordinates $x = 9$ is

• A. $4 a ^ { 2 }$
• B. $4 a ^ { 2 } .4$
• C. $4 a ^ { 2 } ( 9 - 4 )$
• D. $\frac { 152 \sqrt { a } } { 3 }$

Answer 1

Answer: (D)

$\frac { 152 \sqrt { a } } { 3 }$

Answer 2

Shaded area

$A = 2 \int _ { 4 } ^ { 9 } \sqrt { 4 a x } d x$

$A = 4 \sqrt { a } \times \frac { 2 } { 3 } \left[ x ^ { 3 / 2 } \right] _ { 4 } ^ { 9 } = \frac { 152 \sqrt { a } } { 3 }$.