Graphing equations.

J

Jonathan Dolen

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Jun 30, 2005
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Hi all. I have some questions, about graphing equations.


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1. Write the equation of a line with an x-intercept of 1 and a slope of 3.

2. Write the equation of a line with the slopeof -4 and a y-intercept of 3.

3. What is true about the slope of two parallel lines?

4. Write the equation of the line with the slope of 8 passing through the point (4, 1).

5. Write the equation of the line with the points (-2, -5) and (6, -5)

Thank you.
 
Jonathan Dolen said:
1. Write the equation of a line with an x-intercept of 1 and a slope of 3.
Click to expand...

The x-intercept is the value of x when y = 0, so to have an x-intercept of 1 is to pass through the point (1, 0). You have a point and the slope, so you can use the point-slope formula:

. . . . y - y<sub>0</sub> = m(x - x<sub>0</sub>)

where m is the slope of the line and (x<sub>0</sub>, y<sub>0</sub>) is a point on the line.

Jonathan Dolen said:
2. Write the equation of a line with the slopeof -4 and a y-intercept of 3.
Click to expand...

The equation y = mx + b has slope m and y-intercept b. Plug 'em in.

Jonathan Dolen said:
3. What is true about the slope of two parallel lines?
Click to expand...

Parallel lines are defined as lines with the same slope.

Jonathan Dolen said:
4. Write the equation of the line with the slope of 8 passing through the point (4, 1).
Click to expand...

You can use the point-slope formula here, just like in number 1.

Jonathan Dolen said:
5. Write the equation of the line with the points (-2, -5) and (6, -5)
Click to expand...

First, find the slope. The slope is change in y divided by change in x:

. . . . m = (y<sub>1</sub> - y<sub>0</sub>) / (x<sub>1</sub> - x<sub>0</sub>)

Then pick a point and use the point-slope formula.
 
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