Q. What is the particular solution to the differential equation dxdy=(x−3)y with the initial condition y(0)=2 ?
Identify type of differential equation: Identify the type of differential equation.The given differential equation is a first-order linear differential equation in the form dxdy+P(x)y=Q(x), where P(x)=−3 and Q(x)=x. This is also a separable differential equation since it can be written in the form ydy=(x−3)dx.
Separate variables: Separate the variables.We want to get all the y terms on one side and all the x terms on the other side. To do this, we divide both sides by y and multiply both sides by dx to get:y1dy = (x−3)dx
Integrate both sides: Integrate both sides.We integrate the left side with respect to y and the right side with respect to x:∫(1/y)dy=∫(x−3)dxThe integral of 1/y with respect to y is ln∣y∣, and the integral of (x−3) with respect to x is (x2)/2−3x.So we have ln∣y∣=(x2)/2−3x+C, where x0 is the constant of integration.
Solve for constant of integration: Solve for the constant of integration using the initial condition.We are given the initial condition y(0)=2. We plug x=0 and y=2 into the equation ln∣y∣=2x2−3x+C to find C:ln∣2∣=202−3(0)+Cln(2)=C
Write particular solution: Write the particular solution.Now that we have the constant C, we can write the particular solution:ln∣y∣=2x2−3x+ln(2)To solve for y, we exponentiate both sides to get rid of the natural logarithm:∣y∣=e(2x2−3x+ln(2))Since y is positive for y(0)=2, we can drop the absolute value:y=e(2x2−3x)⋅eln(2)y=2e(2x2−3x)
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