Q. dtdy=2y, and y=8 when t=0.Solve the equation.Choose 1 answer:(A) y=e2t(B) y=2e8t(C) y=e8t(D) y=8e2t
Separation of Variables: The given differential equation is dtdy=2y. This is a first-order linear differential equation that can be solved using separation of variables. We will separate the variables y and t to integrate them separately.
Integrating Separated Variables: We rewrite the equation to separate the variables: (1/y)dy=2dt. This allows us to integrate both sides with respect to their respective variables.
Finding Constant of Integration: Integrating both sides, we get: ∫(y1)dy=∫2dt. The integral of (y1)dy is ln∣y∣ and the integral of 2dt is 2t. So we have ln∣y∣=2t+C, where C is the constant of integration.
Substitute Initial Condition: To find the constant of integration C, we use the initial condition given: y=8 when t=0. Substituting these values into the equation ln∣y∣=2t+C, we get ln∣8∣=2(0)+C. This simplifies to ln(8)=C.
Final Solution: Now we have the constant C, which is ln(8). We substitute this back into the equation ln∣y∣=2t+C to get ln∣y∣=2t+ln(8).
Final Solution: Now we have the constant C, which is ln(8). We substitute this back into the equation ln∣y∣=2t+C to get ln∣y∣=2t+ln(8).To solve for y, we exponentiate both sides of the equation to get rid of the natural logarithm: eln∣y∣=e2t+ln(8). This simplifies to ∣y∣=e2t⋅eln(8).
Final Solution: Now we have the constant C, which is ln(8). We substitute this back into the equation ln∣y∣=2t+C to get ln∣y∣=2t+ln(8).To solve for y, we exponentiate both sides of the equation to get rid of the natural logarithm: eln∣y∣=e2t+ln(8). This simplifies to ∣y∣=e2t⋅eln(8).Since eln(8) is simply 8, we have ∣y∣=8e2t. Because y is positive (as given by the initial condition ln(8)1 when ln(8)2), we can drop the absolute value to get ln(8)3.