what is the slope of a line whose graph is parallel to the graph of 3x+y=-8

Question

please explain

Answer 1

Find the slope for

 

3x + y = -8

 

Okay, let's put it in y = mx + b format first (the equation of a straight line, slope-intercept form)

where m is the slope and b is the y-intercept

 

Subtract 3x from both sides to isolate y.

 

3x - 3x + y = -3x -8

 

y = -3x - 8

 

The number -3 is in the m place which indicates the slope.

 

The slope for parallel lines have the same slope, so the answer to your question is -3.

 

You can now determine (x, y) points on the line.

Set up a T-frame for x, y values.

Substitute values for x, beginning with 0.

 

x      y

______

-2    -2

-1    -5

0      -8

1    -11

2    -14

 

If you examine the y-points, you can see that they are -3 apart from each other.

This is a perfect way to check that -3 is the slope.

 

One further way to check slope now that you have points is to use the formula:

 

m = (y2 - y1) / (x2 - x1)

 

Let's use the set of points  (-1, -5) and (0, -8)

 

slope = [ (-8) - (-5) ]  divided by   [(0) - (-1) ] 

 

m = -8 +5 / 1

 

m= -3

Answer 2

Hi Lajuana;

3x+y=-8

The equation is in standard form...

Ax+By=C, A>0

The slope of this line is -A/B.

The slope of this line is -3/1, -3.

Any equation parallel to this, would have identical slope of -3.  However, the value of C would be different.

Answer 3

What Parviz is implying is to put the equation into slope-intercept form (y=mx+b). so subtract 3x to both side and you will find your slope (m), which is the number attached to x once in the slope-intercept form.

Answer 4

2 lines are parallel if and only if they have equal slope.

 

  Find the slope of the given line.