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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.
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