1. y = mx + c

2. Equation of a Straight Line
Is in form
y = mx + c
Ex 1 y = - ¾ x + 2
m = - ¾ , y int (0 , 2)
Ex 2 m = 9, y int (0 , -8)
y = 9x - 8
gradient
Y intercept (0 ,?)

3. Applying new knowledge
Line goes through (0 , 7) and is
to y = 4x + 2.
Equation?
perpendicular
need gradient
m = - ¼
(m1m2 = -1)
y intercept
y = - ¼x + 7

4. And There’s More
What angle does line 2y = 6x + 4 make with the x axis?
m = tanθ
2y = 6x + 4
y = 3x + 2
m = 3
tanθ = 3
θ = tan-1(3) = 71.60 m?

5. Special Cases (annoying lines!) y (0 , 4) Horizontal lines Y = 0x + 4
m = 0 x

6. Special Cases (really annoying!) No y intercept! y Vertical lines
(2 , 4)
m = ∞ x
(2 , 0)
(2 , -2)

7. Special Cases (really annoying!) No y intercept! y Vertical lines
(2 , 4)
m = ∞ x
(2 , 0)
(2 , -2)
Equation x = 2

8. Annoying Lines Equations
Horizontal Lines (m = 0)
are in form y = ? (i.e no x)
Vertical lines (m = ∞)
are in form x = ? (i.e no y) y
Y = 5
(0 , 5)
(7 , 0) x
X = 7