Straight Line Graphs (Year 1 - Chapter 5)

y = mx + c

The Equation of a straight line, stating that the value of y equals the gradient x the given x coordinate + the y intercept.

Gradient

The rate of change of y in terms of x.

Y intercept

The point at which a curve passes through the y axis (the y value when x = 0).

ax + by + c = 0

An alternate equation for straight lines, where a,b and c have to be integers.

Integers

Whole numbers.

y - y1 = m(x - x1)

A way of writing the equation of a straight line when a set of coordinates is known.

Paralell Lines

Lines with the same gradient that do not cross at any point (equal gradient and different y intercept).

Perpendicular Lines

Lines with negative reciprocal gradients (m and -1/m).

Distance between Points

This can be found using pythagoras’ theorem and modelling x and y as the 2 shorter sides of a right angled triangle.