Question

The equation of the straight line joining the point $( a , b )$to the point of intersection of the lines $\frac { x } { a } + \frac { y } { b } = 1$ and $\frac { x } { b } + \frac { y } { a } = 1$ is .

• A. $a ^ { 2 } y - b ^ { 2 } x = a b ( a - b )$
• B. $a ^ { 2 } y + b ^ { 2 } y = a b ( a + b )$
• C. $a ^ { 2 } y + b ^ { 2 } x = a b$
• D. $a ^ { 2 } x + b ^ { 2 } y = a b ( a - b )$

Answer 1

Answer: (A)

$a ^ { 2 } y - b ^ { 2 } x = a b ( a - b )$

Answer 2

The given lines intersect at $\left( \frac { a b } { a + b } , \frac { a b } { a + b } \right)$ and join of this with (a, b) will have slope $\frac { b ^ { 2 } } { a ^ { 2 } }$. Now proceed.