Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Evaluate the integral.

int6x^(3)e^(-2x)dx
Answer:

Evaluate the integral.\newline6x3e2xdx \int 6 x^{3} e^{-2 x} d x \newlineAnswer:

Full solution

Q. Evaluate the integral.\newline6x3e2xdx \int 6 x^{3} e^{-2 x} d x \newlineAnswer:
  1. Identify integral: Identify the integral to be solved.\newlineWe need to evaluate the integral of the function 6x3e2x6x^{3}e^{-2x} with respect to xx. This is an integration problem that requires the use of integration by parts.
  2. Apply integration by parts: Apply integration by parts. Integration by parts is given by the formula udv=uvvdu\int u \, dv = uv - \int v \, du, where uu and dvdv are parts of the integrand. We choose u=x3u = x^3 (which will be differentiated) and dv=6e2xdxdv = 6e^{-2x}dx (which will be integrated).
  3. Differentiate and integrate: Differentiate uu and integrate dvdv. Differentiating uu gives us du=3x2dxdu = 3x^2 dx. Integrating dvdv gives us v=3e2xv = -3e^{-2x} (since the integral of e2xe^{-2x} is 12e2x-\frac{1}{2} e^{-2x} and we have a factor of 66).
  4. Substitute into formula: Substitute uu, vv, dudu, and dvdv into the integration by parts formula.\newlineNow we have all the components to apply integration by parts:\newline6x3e2xdx=uvvdu\int 6x^{3}e^{-2x}dx = uv - \int v du\newline=(3e2x)(x3)(3e2x)(3x2)dx= (-3e^{-2x})(x^{3}) - \int(-3e^{-2x})(3x^{2})dx\newline=3x3e2x+9x2e2xdx= -3x^{3}e^{-2x} + 9\int x^{2}e^{-2x}dx
  5. Apply integration by parts again: Apply integration by parts again to the remaining integral.\newlineWe need to integrate 9x2e2xdx9\int x^2e^{-2x}\,dx. We choose u=x2u = x^2 and dv=9e2xdxdv = 9e^{-2x}\,dx.\newlineDifferentiating uu gives us du=2xdxdu = 2x\, dx.\newlineIntegrating dvdv gives us v=92e2xv = -\frac{9}{2} e^{-2x}.
  6. Substitute into formula again: Substitute uu, vv, dudu, and dvdv into the integration by parts formula for the second time.\newline9x2e2xdx=uvvdu\int 9x^2e^{-2x}dx = uv - \int v du\newline=(92e2x)(x2)(92e2x)(2x)dx= \left(-\frac{9}{2} e^{-2x}\right)(x^2) - \int\left(-\frac{9}{2} e^{-2x}\right)(2x)dx\newline=92x2e2x+9xe2xdx= -\frac{9}{2} x^2e^{-2x} + 9\int xe^{-2x}dx
  7. Integrate exponential function: Apply integration by parts for the third time to the remaining integral.\newlineWe need to integrate 9xe2xdx9\int xe^{-2x}\,dx. We choose u=xu = x and dv=9e2xdxdv = 9e^{-2x}\,dx.\newlineDifferentiating uu gives us du=dxdu = dx.\newlineIntegrating dvdv gives us v=92e2xv = -\frac{9}{2} e^{-2x}.
  8. Combine all parts: Substitute uu, vv, dudu, and dvdv into the integration by parts formula for the third time.\newline9xe2xdx=uvvdu\int 9xe^{-2x}dx = uv - \int v du\newline=(92e2x)(x)(92e2x)dx= \left(-\frac{9}{2} e^{-2x}\right)(x) - \int\left(-\frac{9}{2} e^{-2x}\right)dx\newline=92xe2x+92e2xdx= -\frac{9}{2} xe^{-2x} + \frac{9}{2} \int e^{-2x}dx
  9. Combine all parts: Substitute uu, vv, dudu, and dvdv into the integration by parts formula for the third time.\newline9xe2xdx=uvvdu\int 9xe^{-2x}dx = uv - \int v du\newline=(92e2x)(x)(92e2x)dx= \left(-\frac{9}{2} e^{-2x}\right)(x) - \int\left(-\frac{9}{2} e^{-2x}\right)dx\newline=92xe2x+92e2xdx= -\frac{9}{2} xe^{-2x} + \frac{9}{2} \int e^{-2x}dxIntegrate the remaining exponential function.\newlineThe integral of e2xe^{-2x} is 12e2x-\frac{1}{2} e^{-2x}, so we have:\newline92e2xdx=94e2x\frac{9}{2} \int e^{-2x}dx = -\frac{9}{4} e^{-2x}
  10. Combine all parts: Substitute uu, vv, dudu, and dvdv into the integration by parts formula for the third time.\newline9xe2xdx=uvvdu\int 9xe^{-2x}dx = uv - \int v du\newline=(92e2x)(x)(92e2x)dx= \left(-\frac{9}{2} e^{-2x}\right)(x) - \int\left(-\frac{9}{2} e^{-2x}\right)dx\newline=92xe2x+92e2xdx= -\frac{9}{2} xe^{-2x} + \frac{9}{2} \int e^{-2x}dxIntegrate the remaining exponential function.\newlineThe integral of e2xe^{-2x} is 12e2x-\frac{1}{2} e^{-2x}, so we have:\newline92e2xdx=94e2x\frac{9}{2} \int e^{-2x}dx = -\frac{9}{4} e^{-2x}Combine all parts to get the final answer.\newlineNow we combine all the parts from the previous steps:\newlinevv00\newlineThis is the final answer, where vv11 is the constant of integration.

More problems from Find indefinite integrals using the substitution and by parts