Q. If dxdy=ky where k is a constant, and y(0)=100, then y(3)A. 100ekdxdy=ky→∫y1dy+(kdxB. 300ekln(y)=kx+cC. 100e3kln()=D. 300e3k
Separate and Integrate: Solve the differential equation dxdy=ky. To solve this first-order linear differential equation, we separate variables and integrate both sides.
Perform Integration: Separate variables and integrate.We write the equation as (y1)dy=kdx and integrate both sides.∫(y1)dy=∫kdx
Solve for y: Perform the integration.The integral of y1dy is ln∣y∣, and the integral of kdx is kx. So we have:ln∣y∣=kx+C, where C is the constant of integration.
Determine Constant C: Solve for y.To solve for y, we exponentiate both sides of the equation to get rid of the natural logarithm.eln∣y∣=ekx+C∣y∣=ekx⋅eCSince y is positive (given y(0)=100), we can drop the absolute value:y=ekx⋅eC
Substitute for C: Determine the constant C using the initial condition y(0)=100. Substitute x=0 and y=100 into the equation y=ekx⋅eC to find C. 100=ek⋅0⋅eC100=e0⋅eC100=1⋅eCC0
Substitute C into y: Substitute C back into the equation for y. y=ekx⋅eln(100) y=ekx⋅100
Find y(3): Find y(3).Substitute x=3 into the equation y=ekx×100 to find y(3).y(3)=ek×3×100y(3)=100e3k
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