Integral of a sqrt of polynomial

So I got (1/4)ln(4/5) + (1/4)ln(2) + (1/4)arctan(4/3).In summary, the given integral can be solved by realizing that 1 + tan^2(theta) = sec^2(theta) and changing the integration limits appropriately. The resulting solution is (1/4)ln(4/5) + (1/4)ln(2) + (1/4)arctan(4/3).
  • #1
ldbaseball16
40
0

Homework Statement


(1/sqrt(x^2+16), x, 0, 4);


Homework Equations


x=4tan(theta)
dx=4sec^2(theta)d(theta)


The Attempt at a Solution


(1/sqrt(16+(4tan(theta))^2)(4sec^2theta) I am confused can i get some help??
 
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  • #2


ldbaseball16 said:

Homework Statement


(1/sqrt(x^2+16), x, 0, 4);


Homework Equations


x=4tan(theta)
dx=4sec^2(theta)d(theta)


The Attempt at a Solution


(1/sqrt(16+(4tan(theta))^2)(4sec^2theta) I am confused can i get some help??

If you remember that

[tex] 1 + tan^2 \theta = sec^2 \theta [/tex]

then you'll find that the integrand simplifies quite nicely. Don't forget to change your integration limits appropriately.
 
  • #3


ok, i got ln(4/sqrt(x^2 +16) + (x/4)? is this right?
 
  • #4


hmmm... if this is a definite you don't need to try and convert back to x's, just change the integration limits when you make the variable change
 
  • #5


ldbaseball16 said:
ok, i got ln(4/sqrt(x^2 +16) + (x/4)? is this right?

I think that's pretty close. As the previous post mentions, I didn't change back to the x's but worked with theta limits of 0 to pi/4.
 

1. What is the definition of an integral of a square root of a polynomial?

The integral of a square root of a polynomial is a mathematical operation that represents the area under the curve of the square root function. It is denoted by the symbol ∫ and is used to find the total value of the function within a given interval.

2. How is the integral of a square root of a polynomial calculated?

The integral of a square root of a polynomial can be calculated using various methods such as substitution, integration by parts, or trigonometric substitution. It involves breaking the function into smaller, simpler components and using mathematical rules to solve for the integral.

3. What is the significance of finding the integral of a square root of a polynomial?

The integral of a square root of a polynomial is an important tool in calculus and is used to solve various real-world problems. It helps in finding the area, volume, and other physical quantities of complex shapes and objects. It also helps in finding the average value of a function and in calculating the work done by a variable force.

4. Can the integral of a square root of a polynomial have negative values?

Yes, the integral of a square root of a polynomial can have negative values. The negative value represents the area below the x-axis, while the positive value represents the area above the x-axis. The net value of the integral is the difference between the positive and negative areas.

5. Is there a specific method to solve for the integral of a square root of a polynomial?

There are various methods to solve for the integral of a square root of a polynomial, and the choice of method depends on the complexity of the function. Some common methods include substitution, integration by parts, and trigonometric substitution. It is important to choose the right method to ensure accurate results.

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