asked 10.1k views
0 votes
If z = x² − xy + 4y² and (x, y) changes from (2, −1) to (1.96, −0.95), compare the values of Δz and dz. (Round your answers to four decimal places.) dz = Δz =

asked
User LueTm
by
8.2k points

1 Answer

5 votes

Answer:

To compare the values of Δz and dz, we need to calculate both values.

Δz represents the change in z, which is the difference between the final value of z and the initial value of z.

dz represents the differential of z, which is the partial derivative of z with respect to x multiplied by the change in x, plus the partial derivative of z with respect to y multiplied by the change in y.

Let's calculate both values:

1. Δz = z(final) - z(initial)

Plug in the values of (x, y) = (1.96, -0.95) into the equation z = x² - xy + 4y² to find z(final).

Plug in the values of (x, y) = (2, -1) into the equation z = x² - xy + 4y² to find z(initial).

Calculate the difference between z(final) and z(initial) to find Δz.

2. dz = (∂z/∂x) * Δx + (∂z/∂y) * Δy

Calculate the partial derivative of z with respect to x, (∂z/∂x).

Calculate the partial derivative of z with respect to y, (∂z/∂y).

Plug in the values of Δx = (1.96 - 2) and Δy = (-0.95 - (-1)) into the equation to find dz.

Round both Δz and dz to four decimal places for the final comparison.

I hope this helps! Let me know if you have any other questions.

Explanation:

let's break it down step by step:

1. Δz represents the change in z, which is the difference between the final value of z and the initial value of z.

- Calculate z(final): Substitute the values (x, y) = (1.96, -0.95) into the equation z = x² - xy + 4y².

- Calculate z(initial): Substitute the values (x, y) = (2, -1) into the equation z = x² - xy + 4y².

- Calculate Δz by finding the difference between z(final) and z(initial).

2. dz represents the differential of z, which is the partial derivative of z with respect to x multiplied by the change in x, plus the partial derivative of z with respect to y multiplied by the change in y.

- Calculate (∂z/∂x): Take the partial derivative of z = x² - xy + 4y² with respect to x.

- Calculate (∂z/∂y): Take the partial derivative of z = x² - xy + 4y² with respect to y.

- Substitute the values Δx = (1.96 - 2) and Δy = (-0.95 - (-1)) into the equation dz = (∂z/∂x) * Δx + (∂z/∂y) * Δy.

Round both Δz and dz to four decimal places for the final comparison.

I hope this clarifies the step-by-step process! Let me know if you have any other questions.