WarmUp 38
January, 2004
Notes
I
slope - intercept form ( ‘y’ form )
y = m x +
b m
= slope of the line
b =
‘y’ intercept
in ‘y’ form
y = 2x + 3
slope (m) = 2 or
2
1
‘y’ intercept = 3 (0, 3)
Example
Linear equation 2y - 6x
= 12,
‘y’ form (slope-intercept form)
2y - 6x + 6x
= 6x + 12
(add 6x)
2y = 6x + 12
(simplify)
(1/2) (2y) = (6x +
12) (1/2) (multiply by reciprocal of 2)
y = 3x + 6
~ the slope is
3 the ‘y’ intercept
is ( 0, 6)
~ is point (4, 2) on the
line 2y - 6x = 12
Does 2(2) - 6(
4) = 12 ? 4 - 24
= 12
No - therefore point (4, 2) does NOT lie on
the line 2y - 6x = 12
Examples
~
In the linear equation 5y -
15x = 20,
~ in
‘y form (slope-intercept form)
~ the
slope is ______ the ‘y’ intercept
is ______
~ is
point (3, 9) on this line ?
~
In the linear equation
3y - 4x = 12,
~ in
‘y form (slope-intercept form)
~ the
slope is ______ the ‘y’ intercept
is ______
~ is
point (2, 8) on this line ?
~
Identify the slope and the ‘y’ intercept
of the graph of the following equations.
y = mx
+ b
y =
3x - 2
y = 4 x + 4
5
slope ____
slope ____
‘y’ intercept (0, ___ )
‘y’ intercept
(0, ___ )
Notes
slope
= change in ‘y’
(rise)
slope of line connecting (5, 6)
and (3, 2)
change
in ‘x’ (run)
slope
= 6 - 2 = 4
= 2 or
2 - 6 = - 4
= 2
5 - 3 2
3 - 5
- 2
slope = 2 rise
1 run
~ Find the slopes of the line through each pair of points.
Point B
(6, 8) and (3, 2)
Point A
(-1, 4) and ( -3, -7)