Integration using u substitution

In summary, to evaluate the integral of (x+1)5^(x+1)^2, set u=(x+1) and du=dx. The integral becomes u*5^u^2. Then, try another u type substitution, w=u^2, and review integration formulas for a^x.
  • #1
thegoosegirl42
22
1

Homework Statement


Evaluate the integral of (x+1)5^(x+1)^2

Homework Equations

The Attempt at a Solution


I set my u=(x+1) making du=1dx. This makes it u*5^u^2. I integrated the first u to be ((x+1)^2/2) however I don't know what to do with the 5^u^2
 
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  • #2
thegoosegirl42 said:

Homework Statement


Evaluate the integral of (x+1)5^(x+1)^2

Homework Equations

The Attempt at a Solution


I set my u=(x+1) making du=1dx. This makes it u*5^u^2. I integrated the first u to be ((x+1)^2/2) however I don't know what to do with the 5^u^2

You don't do integrals in pieces like that. Assuming that what you have is ##\int u 5^{u^2}~du## try another u type substitution ##w = u^2##. You may need to review your integration formulas for ##\int a^x~dx##.
 

FAQ: Integration using u substitution

What is u substitution and when is it used?

U substitution is a technique used in integration to replace a complex expression with a simpler one in order to make the integration process easier. It is typically used when an integral contains a function within another function, such as a polynomial within a trigonometric function.

How do you choose the substitution for u?

The substitution for u is typically chosen based on the expression within the integral. It should be a function that when differentiated, will result in some or all of the terms in the original integral. Common choices for u include trigonometric functions, exponential functions, and polynomials.

How do you perform u substitution?

To perform u substitution, follow these steps:

  1. Identify the function within the integral that will be substituted as u.
  2. Calculate du, the derivative of u, with respect to the variable of integration.
  3. Replace the chosen function with u and the derivative of u with du in the integral.
  4. Integrate the new integral with respect to u.
  5. Replace u with the original function in the final answer.

Can u substitution be used for all integrals?

No, u substitution is most effective when the integral contains a function within another function. It may not be useful for integrals with complicated expressions or those that require other integration techniques, such as integration by parts.

How do you know if u substitution was successful?

If the integral after the substitution is simpler or easier to integrate than the original, then the substitution was successful. It should also result in an answer that matches the original integral when u is replaced with the original function.

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