The line crosses the y-axis at (0, 5). The number 5 is called the y-intercept of the equation of the line. The line crosses the x-axis at (2, 0). Thus, 2 is the x-intercept of the equation of the line.
In Lesson
7–2, you learned how to write an equation in point-slope form by using the
slope and a point on the line, and two points on the line. You can also write
an equation of a line if you know the slope and y-intercept. Consider
the graph below, which crosses the y-axis at (0, b).
Example
Write an
equation in slope-intercept form of each line with the given slope and y-intercept.
3. m = 0, b = 3
Alternative Solutions:
y = mx
+ b Slope-Intercept Form
= 0x
+ 3 Replace
m with 0 and b with 3.
= 3 Simplify.
The equation of the line
is y = 3. Remember that a line with a slope of 0 is a horizontal line.
Now you can
use the methods in Lesson 7–2 to write equations in slope-intercept form.
Example
Write an
equation of the line in slope-intercept form for each situation.
4.
slope
1 and passes through (2, 5)
Alternative Solutions:
An equation of the line
is y = x + 3. What are the x- and
y-intercepts?
5.
passing
through (4, 4) and (2, 1)
Alternative Solutions:
First, determine the
slope of the line.
Now substitute the known
values into the point-slope form.
Then write in
slope-intercept form.
An equation of the line is 
. You can see from the graph that the y-intercept
is 2. You can also check by substituting the
coordinates of one of the points into the equation.
Example
Science Link
6.
A
California inventor designed the Skycar, a car that can fly. The graph represents
its landing from 50 meters off the ground. Write an equation of the line in
slopeintercept form.
Alternative Solutions:
The y-intercept of the
line is 50. Determine the slope.
Now substitute these
values into the slope-intercept form.
An equation of the line is y =
–2x + 50.
Sumber
Thanks for reading Writing Equations in Slope-Intercept Form. Please share...!
