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Question 83840: Can you please help me find the equation of the problem with a slope of 2 and the points (4,-8)
Found 2 solutions by jim_thompson5910, Earlsdon:
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website!
| 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, -8)
- it has a slope of 2
First, let's draw a diagram of the coordinate system with point (4, -8) 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=2, 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:
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Answer by Earlsdon(6294) (Show Source):
You can put this solution on YOUR website! You can start by writing the slope-intercept form of a linear equation.
1) y = mx+b (m = slope, b = y-intercept)
You have been given the slope, m = 2, so now you can write:
2) y = 2x + b Now you need to find the value of b.
You can do this by substituting the x- and y-coordinates from the given point (4, -8) into equation 2) and solving for b.
-8 = 2(4) + b
-8 = 8 + b Subtract 8 from both sides.
-16 = b Now that you have b, you can write the final equation.
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