As the circle passes through origin and makes intercepts 2 units and 4 units on x-axis and y-axis respectively, it passes through the points A(2,0) and B(0,4). Since axes are perpendicular to each other, therefore, ∠AOB=90∘ and hence AB
becomes a diameter of the circle. So, the equation of the required circle is (x−2)(x−0)+(y−0)(y−4)=0
or x2+y2−2x−4y=0.