Question

The differential equation of all circles in the first quadrant which touch the coordinate axes is of order

• A. 2
• B. 3
• C. 4
• D. None of these

Answer 1

Answer: (A)

2

Answer 2

The equation of the family of circle which touch both the axes is $( x - a ) ^ { 2 } + ( y - a ) ^ { 2 } = a ^ { 2 }$where a is a parameter. This is one parameter family of curves. So its differential equation is of order one.