If xy = 4225 where x, y are natural numbers, then what is the minimum value of x + y ?

What does the equation $x \frac{dy}{dx}-2y= 0$ represent ?

If the points with coordinates (-5, 0), (5p², 10p) and (5q², 10q) are collinear, then what is the value of pq where p ≠ q ?

What is the equation of the straight line which passes through the point (1, -2) and cuts off equal intercepts from the axes ?