A point is translated on the coordinate plane from (4,−1) to (4,2) . Journey writes the function g(y)=y+k to describe the translation. What is the value of k?

A. -5
B. 3
C. -3
D. 0

1 answer

To determine the value of \( k \) in the function \( g(y) = y + k \) that describes the translation from the point \( (4, -1) \) to the point \( (4, 2) \), we first consider the change in the \( y \)-coordinate.

The original point has a \( y \)-coordinate of \(-1\), and the new point has a \( y \)-coordinate of \(2\). The translation can be described as:

\[ y + k = 2 \]

We can set up the equation with the original \( y \)-coordinate:

\[ -1 + k = 2 \]

Now, solve for \( k \):

\[ k = 2 + 1 \] \[ k = 3 \]

Thus, the value of \( k \) is \( 3 \). The correct answer is:

B. \( 3 \)