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Further Problems on Separation of variables, implicit/explicit solutions (8) A s

ID: 2878442 • Letter: F

Question

Further Problems on Separation of variables, implicit/explicit solutions (8) A simple first order ODE with an independent variable x is given as: y =y Show by method of separation of variable that a solution is obtainable with A = ec where c is an arbitrary constant. (Hint: Your solution step should not be more than 4 or 5 lines) (9) Solve following problems using method of separation of variables. Is the appropriate solution that you selected implicit or explicit? 2 dy dx (iv) y' = y2 ln (ty) 11) 1 = 2i

Explanation / Answer

8. y' = y

=> dy/dx = y

=> dy/y = dx

on integrating both sides

=> ln y = x + c [where c is a constant]

=> y= A.ex [ A = ec ]

9. (i) y' = x2/y

=> ydy = x2dx

On integrating both sides

=> y2/2 = x3/3 + c

Explicit

(ii) i' = (1+2t)/2i

=> di/dt = (1+2t)/2i

=> 2i di = (1+2t) dt

On integrating both sides

=> i2 = t + t2 + c

Explicit

(iii) dy/dx = x / (1+y2)

=> (1+y2) dy = x dx

On integrating both sides

=> y + y3/3 = x2/2 + c

Explicit