Linear Graphs and y = mx + c
A graph that has a straight line is called a linear graph:
The vertical axis is the y-axis, while the horizontal axis is called the x-axis
The gradient, or slope, of the line is given the symbol 'm'
The line crosses the y-axis when x = 0 at the y-intercept, given the symbol 'c'
Calculating the gradient, or slope, of a linear graph is an important skill to master:
Draw a large triangle onto the line
Work out the coordinates of the two points where the triangle meets the line
Divide the change in y value by the change in x value
Calculating Gradients: Example A
A worked example where the gradient of a straight line is calculated.
Calculating Gradients: Example B
Another example of how to calculate the gradient of a line.
Drawing Tangents to a Curve [often higher tier only]
Sometimes you need to work out the slope at a particular point on a curve:
Carefully draw a straight line with a ruler that just touches the curve
Work out the gradient of this straight line in the usual way
A worked example where a tangent is used to find the gradient of a curve at a point.
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