There are two basic forms of an equation of the line, the
point-slope and the standard form.
(the standard is sometimes also called the
slope-intercept
form).
Standard:
y
= mx+n (1)
where m - the slope of the line and n - the
y-intercept (the value of y when
x=0)
Point-Slope:
(y-y1)
= m(x-x1) (2)
where m is the slope and (x1,y1) is the
given point.
We'll substitute the first pair slope-given
point in (2):
Point slope: y - 3 = -2(x -
1)
We'll remove the
brackets:
y - 3 = -2x +
2
We'll put the equation in the standard form by adding 3
both sides:
y = -2x + 2 +
3
Standard: y = -2x +
5
We'll do the same thing with the next
given pair: (-6;3),
m=-2/3.
Point-Slope:
y - 3 = (-2/3)(x + 6)
We'll remove the
brackets:
y - 3 = -2x/3 -
4
We'll add 3 both sides:
y =
-2x/3 - 4 + 3
y = -2x/3 -
1
Standard:
y = -2x/3 - 1
No comments:
Post a Comment