4  Formation of a Differential Equation whose General Solution is given
We know that the equation
x2 + y2 + 2x – 4y + 4 = 0 (1)
represents a circle having centre at (–1, 2) and radius 1 unit © NCERT
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MATHEMATICS
386
Differentiating equation (1) with respect to x, we get
dy
dx  =
1
2
x
y
−+
 (y ≠ 2) (2)
which is a differential equation