Q. dxdy=−4y, and y=3 when x=2. Solve the equation.
Identify Type and Method: Identify the type of differential equation and the method to solve it.The given differential equation dxdy=−4y is a first-order linear homogeneous differential equation. The method to solve such an equation is to find the integrating factor and then integrate both sides.
Solve Differential Equation: Solve the differential equation.The general solution to the differential equation dxdy=−4y can be found by separating variables. We can rewrite the equation as ydy=−4dx and then integrate both sides.
Perform Integration: Perform the integration on both sides.∫(y1)dy=∫(−4)dxln∣y∣=−4x+C, where C is the constant of integration.
Solve for y: Solve for y.To solve for y, we exponentiate both sides of the equation:eln∣y∣=e(−4x+C)y=e(−4x)⋅eCSince eC is just a constant, we can rename it as C′:y=C′e(−4x)
Use Initial Condition: Use the initial condition to find the value of C′. We are given that y=3 when x=2. We substitute these values into the equation to solve for C′: 3=C′e(−4⋅2)3=C′e(−8)C′=e(−8)3
Calculate C′ Value: Calculate the value of C′.C′=e−83=3×e8
Write Final Solution: Write the final solution with the value of C′.The final solution to the differential equation with the initial condition is:y=(3⋅e8)e−4x
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