Chapter 1 - Linear Equations Formulas

Linear Equation Formula

y = mx + c

What is ‘c’

y-intercept

What is ‘k’

Constant

What is ‘m’

Gradient

Formula to find line segment AB

AB² = (y2-y1)²+(x2-x1)²

How to tell if lines are parallel

m1 = m2

Forumula to find mid point of two coordinates

Mx = x1+x2/2

My = y1+y2/2

How to find the gradient with two points

M = y2-y1/x2-x1

Formula of gradient

m = rise/run

How to know if lines are perpendicular

m1*m2=-1

How to know if lines are perpendicular given one gradient

m2 =-1/m1

Finding equation formula

y-y1 = m(x-x1)

Rule for dividing or multiply negative numbers in inequalities

Swap the inequality sign

Rule for same sign elimination

Subtract the equations

Rule for different signs elimination

Add the two equations

Shortcut for finding the gradient of perpendicular lines

Swap the sign (±) and swap the numerator and denominator

When finding pro-numeral using length of line segment

Square root answer can be ± ; two solutions

y = k

Straight horizontal line, m = 0

x = k

Straight vertical line, m = undefined