Post

Created by @nathanedwards
 at November 1st 2023, 12:34:26 am.

AP Calculus AB Exam Question:

Consider the curve defined by the equation

y=4x2−2x+3y = 4x^2 - 2x + 3

Find the length of the curve between x=−1x = -1 and x=2x = 2.

Step-by-step Solution:

To find the length of the curve, we will use the formula for arc length of a curve:

L=∫ab1+(f′(x))2 dxL = \int_a^b \sqrt{1 + \left(f'(x)\right)^2} \, dx

where aa and bb are the x-values of the starting and ending points of the curve, and f′(x)f'(x) represents the derivative of the function f(x)f(x).

First, let's find the derivative of the function f(x)f(x):

y=4x2−2x+3y = 4x^2 - 2x + 3
y′=8x−2y' = 8x - 2

Now, substitute the equation into the arc length formula:

L=∫−121+(8x−2)2 dxL = \int_{-1}^{2} \sqrt{1 + (8x - 2)^2} \, dx

To simplify the integral, we need to square the expression inside the square root:

L=∫−121+64x2−32x+4 dxL = \int_{-1}^{2} \sqrt{1 + 64x^2 - 32x + 4} \, dx
L=∫−1264x2−32x+5 dxL = \int_{-1}^{2} \sqrt{64x^2 - 32x + 5} \, dx

Since this integral does not have an elementary solution, we will use numerical methods (such as a calculator or computer software) to evaluate it.

Using numerical methods, we find that the length of the curve between x=−1x = -1 and x=2x = 2 is approximately 8.093 units.

Therefore, the length of the curve is 8.093 units.

Note: Calculators or computer software are usually allowed on the AP Calculus AB exam for numerical calculations.