Integrating sqrt(1+4x^2) from x = 0 to x = 1: A Step-by-Step Solution

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I recommend a daily dose of humility and self-deprecation. And never get too confident about your own understanding. Always be a bit skeptical and keep checking yourself.
  • #1
applestrudle
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Homework Statement



Integrate sqrt(1+4x^2)

limits x = 0 to x = 1

Homework Equations


The Attempt at a Solution



let 2x = sinhu

I = 0.5 ∫ (coshu)^2du

limits u = 0 u = sinh^-1(2)

0.5 ∫ (e^2u +e^-2u +2)/4 du

0.5 [(e^2u)/8 -(e^-2u)/8 +2u]

I = 2.56 which is wrong :(

why is it wrong?

please help!
 
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  • #2
applestrudle said:

Homework Statement



Integrate sqrt(1+4x^2)

limits x = 0 to x = 1

Homework Equations





The Attempt at a Solution



let 2x = sinhu

I = 0.5 ∫ (coshu)^2du

limits u = 0 u = sinh^-1(2)

0.5 ∫ (e^2u +e^-2u +2)/4 du

0.5 [(e^2u)/8 -(e^-2u)/8 +2u]

I = 2.56 which is wrong :(

why is it wrong?

please help!

Well, for one thing 0.5 ∫ (e^2u +e^-2u +2)/4 du becomes
0.5 [(e^2u)/8 -(e^-2u)/8 +u/2]. Did you forget to divide the last term by 4?
 
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  • #3
You started out well. I think you made an arithmetic mistake when you multiplied your expression through by .5 -- you got ##e^{2u}/8 + e^{-2u}/8 +2u##. Where did you get 2u. Shouldn't it be u/4?
 
  • #4
what a silly mistake, i feel embarrassed :S
 
  • #5
I recently wrote that 25 is divisible by 3. And just a few months ago based a proof on the non-fact that 10 is prime. Talk about embarrassed. Losing a factor of 4 is much more understandable.

We cannot escape these boneheaded errors.
 

1. What is the basic concept of integration?

The basic concept of integration is finding the area under a curve. It is the inverse process of differentiation and involves finding the antiderivative of a function.

2. How do you integrate a square root function?

To integrate a square root function, you can use the substitution method or integration by parts. In this case, we can use the substitution method by letting u = 1 + 4x^2, which simplifies the integral to ∫√u du.

3. What is the general formula for integrating √(1+4x^2)?

The general formula for integrating √(1+4x^2) is ∫√(1+4x^2) dx = (1/4)∫√u du = (1/8)(u√u + ln|u|) + C, where u = 1 + 4x^2.

4. Can the integral of √(1+4x^2) be evaluated using basic integration rules?

No, the integral of √(1+4x^2) cannot be evaluated using basic integration rules. It requires the use of advanced integration techniques such as substitution or integration by parts.

5. What is the significance of integrating √(1+4x^2) in scientific research?

The integration of √(1+4x^2) is commonly used in physics and engineering to calculate the work done by a varying force. It is also used in calculating the arc length of a curve in mathematics and has applications in other fields such as economics and biology.

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