37.0k views
4 votes
Find the length L of the arc formed by y = (1/8)(-4x² + 2ln(x)) from x = 3 to x = 7. Set up: L = ∫[3 to 7] √(1 + (f'(x))²) dx where f'(x) is the derivative of y with respect to x.

User Shucao
by
6.7k points

1 Answer

4 votes

Final answer:

To find the length L of the arc formed by the equation y = (1/8)(-4x² + 2ln(x)) from x = 3 to x = 7, we can use the formula for arc length. By finding the derivative of y with respect to x and plugging it into the arc length formula, we can evaluate the integral and find the length of the arc to be 2.5 units.

Step-by-step explanation:

To find the length L of the arc formed by the equation y = (1/8)(-4x² + 2ln(x)) from x = 3 to x = 7, we can use the formula for arc length:

L = ∫ [3 to 7] √(1 + (f'(x))²) dx

First, let's find the derivative of y with respect to x:

y' = (1/8)(-8x + 2/x) = -x + 1/4x

Now, we can plug in the derivative into the arc length formula:

L = ∫ [3 to 7] √(1 + (-x + 1/4x)²) dx

Simplifying the expression inside the square root:

L = ∫ [3 to 7] √(1 + x² - 1/2x + 1/16x²) dx

L = ∫ [3 to 7] √((17/16)x² - (1/2)x + 1) dx

Now, integrate the expression:

L = ∫ [3 to 7] √(17/16)x² - (1/2)x + 1 dx

L = ∫ [3 to 7] √(289/256)x² - (17/32)x + 17/16 dx

L = ∫ [3 to 7] (17/16)x - (17/32)x + 17/16 dx

L = ∫ [3 to 7] (1/16)x dx

Integrating gives:

L = (1/16) * (7² - 3²) = (1/16) * 40 = 2.5

Therefore, the length of the arc is 2.5 units.

User APCM
by
9.1k points