A line passes through the point (4,-2) and has a slope of .5. what is an equation for this line in standard form?

A) 1/2x+y=-6
B) -1/2x+y=6
C)1/2x+y=4
D)-1/2x+y=-4

1 answer

To find the equation of the line in standard form, we can start with the slope-intercept form of the line, which is given by the equation:

\[ y = mx + b \]

where \( m \) is the slope and \( b \) is the y-intercept. Given that the slope \( m = 0.5 \), we can substitute that into the equation:

\[ y = 0.5x + b \]

Next, we use the point (4, -2) to find \( b \). Substituting \( x = 4 \) and \( y = -2 \):

\[ -2 = 0.5(4) + b \]

Calculating \( 0.5(4) \):

\[ -2 = 2 + b \]

Now, solving for \( b \):

\[ b = -2 - 2 = -4 \]

So the equation of the line in slope-intercept form is:

\[ y = 0.5x - 4 \]

To convert this to standard form \( Ax + By = C \), we can rearrange it:

\[ 0.5x - y = 4 \]

Next, we can eliminate the decimal by multiplying the entire equation by 2:

\[ 2(0.5x) - 2y = 2(4) \] \[ x - 2y = 8 \]

This doesn't match any of the given options yet, so let's rewrite in a more standard form. Adding \( 2y \) to both sides gives us:

\[ x + 2y = 8 \]

Now we can rearrange it to match the form that is presented in the options. We can rewrite it as:

\[ -1/2x + y = -4 \]

This matches option D:

\[ D) -\frac{1}{2}x + y = -4 \]

To verify the form matches, if we add \(\frac{1}{2}x\) to both sides:

\[ y = \frac{1}{2}x - 4 \]

Thus, the equation you can choose as the answer which represents the line in standard form is option D) \(-\frac{1}{2}x + y = -4\).

Summarizing, the answer is:

D) -1/2x+y=-4