Integration (by substitution?)

In summary, it seems that the conversation is discussing how to integrate the function x^2+7x+10 dx over x+2. The method of substitution is mentioned, but it is noted that the function cannot be integrated at x=-2. The conversation then shifts to discussing the existence of the integral in a region containing x=-2 and whether or not the function with a removable discontinuity can be integrated. Finally, it is mentioned that both x^2 and (x^2)(x+1)/(x+1) are integrable, but the latter is not continuous.
  • #1
Guero
15
0
how can i integrate:
x^2+7x+10 dx
x+2

i assume it's by substitution, but i can't work it out.

sorry for the formatting, btw
 
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  • #2
Factor the top, it cancels.
 
  • #3
Guero said:
how can i integrate:
x^2+7x+10 dx
x+2

i assume it's by substitution, but i can't work it out.

sorry for the formatting, btw

(x+5)(X+2) =x+5
(x+2)
I don't know nothing about integrate. But I think you have to factor the trinomial then divide.
 
  • #4
Note the singularity at x = -2, it can't be integrated in a region containing this point.
 
  • #5
Not really.It can't be defined at x=-2,which means that automatically that point is excluded from the integration domain.

Daniel.
 
  • #6
thanks. should've seen it.
 
  • #7
Does the integral

[tex] \int_{-3}^1 \frac{x^2+7x+10}{x+2} \ dx [/tex] exist, dex? As its written?
 
  • #8
I don't know.U'll have to break it into 2 and evaluate each limit.(I wasn't talking about a definite integral,so your (counter)example is useless).

Daniel.
 
  • #9
whozum said:
Note the singularity at x = -2, it can't be integrated in a region containing this point.

dextercioby said:
Not really.It can't be defined at x=-2,which means that automatically that point is excluded from the integration domain.

Its the same thing.
 
  • #10
However, the integral is a "smoothing" operation. The integral of a function with removable discontinuity exists and is exactly the same as the integral of the function with the discontinuity removed.
 
  • #11
whozum do you agree that x^2 is integratable, what about [tex]\frac{(x^2)(x+1)}{x+1}[/tex]?
 
  • #12
Theyre both integrable, just the latter isn't continuous.
 

What is integration by substitution?

Integration by substitution is a method used in calculus to evaluate integrals. It involves substituting a variable with another expression in order to simplify the integral and make it easier to solve.

Why is integration by substitution important?

Integration by substitution is important because it allows us to solve integrals that would otherwise be difficult or impossible to solve using other methods. It is often used in real-world applications, such as calculating areas and volumes.

How is integration by substitution done?

The process of integration by substitution involves identifying a function within the integral that can be substituted with a new variable. The new variable is then integrated, and the result is substituted back into the original integral.

What are the steps for integration by substitution?

The steps for integration by substitution are: 1) Identify the function to be substituted, 2) Substitute the function with a new variable, 3) Find the derivative of the new variable and substitute it into the integral, 4) Evaluate the new integral, and 5) Substitute the original variable back into the result.

When should integration by substitution be used?

Integration by substitution should be used when the integrand (the expression inside the integral) contains a function that can be simplified by substitution. It is also useful when the integrand contains a product of two functions, as it can be rewritten as a single function using substitution.

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