Question

Find the equation of the line that passes thru (-1,-5) and is parallel to 3x+y=-5. Show work.

Answer 1

Answer:

$y=-3x-8$

Step-by-step explanation:

slope-intercept form:

$y=mx+b$

Start with the given equation, and to find the slope, convert it to slope-intercept form by solving for y.

$3x+y=-5$

In this case, all you need to do is subtract 3x from both sides.

$y=-3x-5$

Here, the slope is -3. The slope of a parallel line will also be -3.

Now, we have 3 known variables. We have the slope and the x and y of a known point. Use those 3 knowns to solve for the 1 unknown, the y-intercept.

$y=mx+b\\-5=(-3)(-1)+b\\-5=3+b\\-8=b\\b=-8$

Finally, with the slope and the y-intercept, you can write the equation of the line:

$y=-3x-8$