|
Question 107078: How would I write the equation of a line that has slope -3 and contain the point(4,2).express final equation in standard form. Showing me how to solve this would be of great assistance.
Thank you,
Brina
Found 2 solutions by Annabelle1, MathLover1:
Answer by Annabelle1(69)   (Show Source):
You can put this solution on YOUR website! you use your point-gradient formula again
y-y1=m(x-x1)
where m=-3 and x1,y1 is your point (4,2)
(x1=4,y1=2)
subbing into the equation
y-2=-3(x-4)
expand
y-2=-3x+12
y+3x-2-12=0
y+3x-14=0
Answer by MathLover1(20850)  (Show Source):
You can put this solution on YOUR website!
here is solution:
| Solved by pluggable solver: FIND a line by slope and one point |
What we know about the line whose equation we are trying to find out:
- it goes through point (4, 2)
- it has a slope of -3
First, let's draw a diagram of the coordinate system with point (4, 2) plotted with a little blue dot:
Write this down: the formula for the equation, given point  and intercept a, is
 (see a paragraph below explaining why this formula is correct)
Given that a=-3, and  , we have the equation of the line:
Explanation: Why did we use formula  ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( ,  ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for (, ):  Here, we know a, , and , and do not know b. It is easy to find out:  . So, then, the equation of the line is:  .
Here's the graph:
|
|
|
|
| |
