# Find the particular solution to the following ODE’s     dy/ dx= 16xe4x subject to y (0) = 3Please explain it step by steps. Thanks

sciencesolve | Teacher | (Level 3) Educator Emeritus

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You need to keep the terms in y to one side and the terms in x to the other side, hence, you need to multiply both sides by dx such that:

`(dy*dx)/(dx) = 16x*e^4x*dx`

Reducing by dx yields:

`dy = 16x*e^4x*dx`

You need to use the reverse of differentiation to find y, hence you need to integrate both sides such that:

`int dy = int 16x*e^4x*dx`

Taking 16 out yields

`int dy = 16int x*e^(4x)*dx`

You should apply integration by parts to solve the right integral. You need to remember the formula of integration by parts.

`int udv = uv - int vdu`

You should consider u = x because differentiating, the power of x decreases.

u=x => du = dx

`dv = e^(4x)dx =gt v = (e^(4x))/4`

`int x*e^(4x)*dx = (x*e^(4x))/4 - int (e^(4x)dx)/4`

Multiplying by 16 both sides, yields:

`16int x*e^(4x)*dx = 16(x*e^(4x))/4 - 16(e^(4x)dx)/16 + c`

`16int x*e^(4x)*dx = 4(x*e^(4x)) - e^(4x) + c`

Factoring out `e^(4x)`  yields:

`16int x*e^(4x)*dx = e^(4x)*(4x - 1) + c`

Hence, `int dy = 16int x*e^(4x)*dx =gt y = e^(4x)*(4x - 1) + c`

You need to find the constant c, hence you need to use the information y(0)=3.

Plugging x=0 in `y = e^(4x)*(4x - 1) + c`  yields:

`y(0) = e^(4*0)*(4*0 - 1) + c =gt y(0) = e^0*(-1) + c`

`y(0) = 1*(-1) + c =gt 3 = -1 + c =gt c = 3 + 1 =gt c = 4`

Hence, evaluating the particular solution of ordinary differential equation yields `y = e^(4x)*(4x - 1) + 4` .