✔ 最佳答案
First, to compare two linear equations, they should both be in the form of
y = mx + b, called the "slope-intercept" format,
where
m = the slope of the line
b = the point where the line intersects (or intercepts) the y-axis (or x = 0)
1. y = 2x + 5 and y = 2x – 1
Both equations are in the point-slope format. Since m = 2 in both equations,
we know that they have the same slope and are therefore parallel.
2. y = x + 4 and x - 3y = - 12
The second equation needs to be changed into the y = mx + b format.
x - 3y = -12
-3y = -x - 12
-3y/-3 = -x/-3 - 12/-3
y = x/3 + 4
y = (1/3)x + 4
The two both have positive slopes, but since they are different slopes they
are not parallel. However, since the have the same y-intercept point, they
intersect at the point (0, 4).
3. y = 5x – 2 and x + 4y = 8
The second equation needs to be changed into the y = mx + b format.
x + 4y = 8
4y = -x + 8
4y/4 = -x/4 + 8/4
y = (-1/4)x + 2
The first equation has a positive slope, while the second equation has a
negative slope. To find their intersection point, do the following:
Set the slope-intercept equations as equal to each other.
5x - 2 = (-1/4)x + 2
5x - 2 = -0.25x + 2
5.25x - 2 = 2
5.25x = 2 + 2
5.25x = 4
5.25x/5.25 = 4/5.25
x = 0.761904762
Insert the above x-value into the first equation to get the y-coordinate of the
two lines' intersection point.
y = 5x – 2
y = 5(0.761905) - 2
y = 3.809524 - 2
y = 1.809524
So, the two lines' point of intersection is (0.76, 1.81).