Question

2. Find the points at which the graph lines of the equations ax + by = 0 and
ax- by = 0 intersect
​

Answer 1

Let us find the slopes of the two lines ax+by=c and bx−ay=c with slopes m  

1

​  

=−  

b

a

​  

 and m  

2

​  

=  

a

b

​  

 respectively.

Now the product of the slopes gives:

m  

1

​  

⋅m  

2

​  

=(−  

b

a

​  

)(  

a

b

​  

)=−1

Therefore, the two lines are perpendicular.

Hence option D is correct.