(2)
x + y = 7 (3)
Chapter 9
DIFFERENTIAL  EQUATIONS
Henri Poincare
(1854-1912 )
© NCERT
not to be republished
MATHEMATICS
380
Let us consider the equation:
xdy
dx +y
 = 0 (4)
We see that equations (1), (2) and (3) involve independent and/or dependent variable
(variables) only but equation (4) involves variables as well as derivative of the dependent
variable y with respect to the independent variable x Such an equation is called a
differential equation