CBSE Class 12 Math 2013 Solved Paper
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Question : 26 of 29
Marks:
+1,
-0
Show that the differential equation dx + (y - 2x ) dy is homogeneous. Find the particular solution of this differential equation, given that x = 0 when y = 1.= 0
Solution:
dx + (y - 2x ) dy = 0
= ... (1)
Let f (x , y) =
Then, (λx , λy) = = [F (x,y)]
Thus, F(x, y) is a homogeneous function of degree zero. Therefore, the given differential equation is a homogeneous differential equation.
Let x = vy
Differentiating w.r.t. y, we get
= v + y
Substituting the value of x and in equation (1), we get
v + y = =
or y = - v
or y = -
or dv = -
or ∫ . dv = - ∫
or = - log |y| + C
Substituting the value of v, we get
+ log |y| = C ... (2)
Substituting x = 0 and y = 1 in equation (2), we get
+ log |1| = C ⇒ C = 2
Substituting the value of C in equation (2), we get
+ log |y| = 2, which is the particular solution of the given differential equation.
= ... (1)
Let f (x , y) =
Then, (λx , λy) = = [F (x,y)]
Thus, F(x, y) is a homogeneous function of degree zero. Therefore, the given differential equation is a homogeneous differential equation.
Let x = vy
Differentiating w.r.t. y, we get
= v + y
Substituting the value of x and in equation (1), we get
v + y = =
or y = - v
or y = -
or dv = -
or ∫ . dv = - ∫
or = - log |y| + C
Substituting the value of v, we get
+ log |y| = C ... (2)
Substituting x = 0 and y = 1 in equation (2), we get
+ log |1| = C ⇒ C = 2
Substituting the value of C in equation (2), we get
+ log |y| = 2, which is the particular solution of the given differential equation.
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