SOLUTION: Find the equation of the line through the point (-2,8) which has slope m=2.

Algebra ->  Linear-equations -> SOLUTION: Find the equation of the line through the point (-2,8) which has slope m=2.      Log On


   

Question 1141416: Find the equation of the line through the point (-2,8) which has slope m=2.
Found 3 solutions by Alan3354, Edwin McCravy, greenestamps:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Do you have a question?

Answer by Edwin McCravy(20065) About Me  (Show Source):
You can put this solution on YOUR website!
Use the point-slope formula:

y-y%5B1%5D=m%28x%5E%22%22-x%5B1%5D%29 substitute x1=-2, y1=8, m=2,

Don't substitute anything for x and y, leave them variable:

y-%288%29=2%28x-%28-2%29%5E%22%22%29

Write (8) as 8 and x-(-2) as x+2

y-8=2%28x%2B2%5E%22%22%29

Distribute on the right:

y-8=2x%2B4%29

Add 8 to both sides:

y=2x%2B10

Edwin

Answer by greenestamps(13215) About Me  (Show Source):
You can put this solution on YOUR website!


...or you can use the slope-intercept form instead of the point-slope form. Many students find this easier.

You know the equation is of the form y=mx+b, with m=2; and that the point (x,y) = (-2,8) is on the line. So

y+=+2x%2Bb
8+=+2%28-2%29%2Bb
8+=+-4%2Bb
12+=+b

The equation is

y+=+2x%2B12

As you get more comfortable with the subject of linear equations, you can get to the answer without the formal mathematics, starting with the equation y = 2x+b:

The point (-2,8) is on the line;
2 times -2 is -4;
what do I need to add to that -4 to get 8? 12

ANSWER: y = 2x+12