Evaluate Integral INT sqrt(x^2+6x) dx | Get Help Now

  • Thread starter Mr. Goosemahn
  • Start date
  • Tags
    Integral
In summary, the process for evaluating the integral INT sqrt(x^2+6x) dx involves using substitution to simplify the expression and then solving it using a trigonometric identity. Substitution is often used in integrals with a polynomial under a square root. Another method for evaluating this integral is integration by parts. A calculator can be used, but it is recommended to understand the steps involved. There are many real-life applications of this integral, such as calculating length, area, and volume, as well as in physics and engineering problems.
  • #1
Mr. Goosemahn
24
0

Homework Statement



Evaluate the integral INT sqrt(x^2+6x) dx

The Attempt at a Solution



I honestly have no clue how to even start. I know it involves trigonometric substitution, but I just can't solve it.

Please Help?
 
Physics news on Phys.org
  • #2
Complete the square.
x^2 + 6x + 9 - 9 = (x + 3)^2 - 3^2.

Now you're set to do a trig substitution. I always draw a triangle, since I don't want to clutter up my brain with what formula goes with what substitution. In that case, the hypotenuse should be x + 3, and either the opposite or adjacent side should be 3.
 

FAQ: Evaluate Integral INT sqrt(x^2+6x) dx | Get Help Now

What is the process for evaluating the integral INT sqrt(x^2+6x) dx?

The process for evaluating this integral involves using substitution to simplify the expression. First, let u = x+3, then du = dx. The integral then becomes INT sqrt(u^2-9) du. Using the substitution u = 3sec(theta), the expression can be simplified further to become INT 3sec(theta) tan(theta) d(theta). This can then be solved using the trigonometric identity cos^2(theta) + sin^2(theta) = 1.

How do I know if I need to use substitution to evaluate this integral?

Substitution is often used in integrals that involve a polynomial under a square root. In this case, the expression x^2+6x can be simplified using the substitution u = x+3. If the integral involves a polynomial under a square root, it is a good indication that substitution may be useful.

Is there another method for evaluating this integral without using substitution?

Yes, there is another method for evaluating this integral without using substitution. You can use integration by parts, where the integral is split into two parts and each part is integrated separately. This method can also be used to solve the integral INT sqrt(x^2+6x) dx.

Can I use a calculator to evaluate this integral?

Yes, you can use a calculator to evaluate this integral. However, the calculator may not show the steps involved in solving the integral. It is always recommended to show your work and understand the steps involved in solving the integral.

Are there any real-life applications of this integral?

Yes, there are many real-life applications of this integral. It can be used to calculate the length of a curve, the area under a curve, and the volume of a solid of revolution. This integral is also commonly used in physics and engineering to solve problems involving velocity, acceleration, and distance.

Similar threads

Replies
12
Views
1K
Replies
22
Views
2K
Replies
44
Views
5K
Replies
5
Views
2K
Replies
3
Views
1K
Replies
4
Views
1K
Replies
5
Views
1K
Back
Top