Q. dxdy=−4y, and y=3 when x=2.Solve the equation.Choose 1 answer:(A) y=3e−4x(B) y=6e−4x(C) y=3e8−4x(D) y=3e4−4x
Recognize Type of Differential Equation: Recognize the type of differential equation. The given differential equation dxdy=−4y is a first-order linear homogeneous differential equation with a constant coefficient.
Solve the Equation: Solve the differential equation.To solve this equation, we can use separation of variables. We rearrange the terms to get ydy=−4dx and then integrate both sides.∫y1dy=∫−4dx
Perform the Integration: Perform the integration.The integral of y1 with respect to y is ln∣y∣, and the integral of −4 with respect to x is −4x. So we have:ln∣y∣=−4x+C, where C is the constant of integration.
Solve for y: Solve for y.To solve for y, we exponentiate both sides to get rid of the natural logarithm:eln∣y∣=e−4x+Cy=e−4x⋅eCSince eC is just a constant, we can rename it as C′:y=C′e−4x
Apply Initial Condition: Apply the initial condition to find C′. We are given that y=3 when x=2. We substitute these values into the equation to find C′: 3=C′e(−4⋅2)3=C′e(−8)C′=e−83
Calculate C′: Calculate the value of C′.To find C′, we calculate e−83:C′=3×e8This is incorrect because we should have divided by e−8, not multiplied. This is a math error.
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