5. Straight Line Graphs Flashcards
1
Q
Gradient
A
(y2-y1) / (x2-x1)
2
Q
How to show that points are collinear
A
You must explain that the gradient is the same AND they share a common point
3
Q
Forms of an equation
A
y = mx + c “Slope-intercept form”
ax + by + c = 0 “Standard” form
y-y1 = m(x-x1)
4
Q
How to find the equation of a line from two points on a line - constant (x1,y1) and variable (x,y)
A
m = (y-y1) / (x-x1)
y-y1 = m(x-x1)
Convert to ax + by + c = 0 if necessary
DO NOT SUBSTITUTE
5
Q
How to find the point two lines meet at
A
Solve the equations simultaneously
6
Q
How to show two lines are perpendicular
A
m1 m2 = -1
7
Q
What to do when you interpret?
A
Use specific values
