Solve the differential equation given that when x = 2, y = 1.
Given and when x = 2, y = 1
This is a first order linear differential equation of the form
Here, and Q = 2y
The integrating factor (I.F) of this differential equation is,
We have
[∵ m log a = log am]
∴ I.F = y–1 [∵ elog x = x]
Hence, the solution of the differential equation is,
We know
⇒ xy–1 = 2y + c
⇒ xy–1 × y = (2y + c)y
∴ x = (2y + c)y
However, when x = 2, we have y = 1.
⇒ 2 = (2 × 1 + c) × 1
⇒ 2 = 2 + c
∴ c = 2 – 2 = 0
By substituting the value of c in the equation for x, we get
x = (2y + 0)y
⇒ x = (2y)y
∴ x = 2y2
Thus, the solution of the given differential equation is x = 2y2