What is an equation of the line that passes through the point (8,-1) and (4,-1)?
1 answer:
Answer:
Step-by-step explanation:
We can start with the general form of the equation for a straight line (may we assume this is a straight line?): y=mx+b. m is the slope (the rate of change of y for a change in x) and b is the y-intercept (the value of y when x=0).
Slope is the Rise of the line (the y axis) and Run is the change in the x axis to create the change in y. The slope is the Rise/Run, which we can find if we have two points on the line.
(8,-1) and (4,-1) will gives us the information to find the slope, m. The Rise is the change in y:
(-1-(-1)) = 0 !!!! It doesn't matter what the change in x is - the slope will be zero. It it weren't zero, it would be calculated as (8 - 4) or 4. The Rise/Run is 0/4 or 0 for this line. It is a flat line! The equation:
y=mx+b
y = 0x + b
y = b
This tells us the value of y will be the y-intercept, which is -1. Y is the same regardless of the value of x.
The equation is y=-4
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Answer: Choice C
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Explanation:
There are four marked points on the line.
Each point is of the form (x,y)
- The first or left most point is (0,1)
- The second point is (2,2)
- The third is (4,3)
- The fourth is (6,4)
Each of these points is then listed in the table format as shown above.
There are infinitely many other points on the line; however, we only select a few of them to make the table (or else we'd be here all day).
Extra side notes:
- The slope of this line is m = 1/2 = 0.5
- The y intercept is 1 located at (0,1)
- The equation of this line is y = 0.5x+1