2.5.1
Graphs & Proportion
Gradient of a Straight Line Graph
Gradient of a Straight Line Graph
For a straight line graph the gradient is the constant of proportionality k. y = kx.
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
y = 2x
y = 2x
- For every increase in x, y increases by twice that amount.
- Since it goes through the origin, y is always double x.
- y is directly proportional to x with k = 2.
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
y = 2x + 3
y = 2x + 3
- This graph shows y = 2x + 3.
- Every increase in x corresponds to twice that increase in y.
- y is not directly proportional to x because of the '+ 3'.
Direct and Inverse Proportions as Graphs
Direct and Inverse Proportions as Graphs
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
Direct proportion
Direct proportion
- If y and x are directly proportional, the graph of the relationship will be a straight line graph.
- It must pass through the origin.
- It could have a negative gradient.
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
Inverse proportion
Inverse proportion
- If y and x are inversely proportional then the graph is a curved line that never touches the x or y axes.
- Part of the graph lies in the top right quadrant and part of the graph lies in the bottom left quadrant.
1Numbers
1.1Integers
1.3Decimals
1.4Powers & Roots
1.5Set Language & Notation
1.6Percentages
1.7Ratio & Proportion
2Equations, Formulae & Identities
2.1Algebraic Manipulation
2.2Expressions & Formulae
2.3Linear Equations
2.4Quadratic Equations
2.5Proportion
3Sequences, Functions & Graphs
3.1Sequences
3.3Graphs
3.4Common Graphs
4Geometry
4.1Angles, Lines & Triangles
4.2Polygons
4.5Circle Properties
4.6Trigonometry & Pythagoras’ theorem
4.7Mensuration of 2D Shapes
4.83D Shapes & Volume
5Vectors & Transformation Geometry
6Statistics & Probability
6.1Statistical Measures
6.2Graphical Representation of Data
Jump to other topics
1Numbers
1.1Integers
1.3Decimals
1.4Powers & Roots
1.5Set Language & Notation
1.6Percentages
1.7Ratio & Proportion
2Equations, Formulae & Identities
2.1Algebraic Manipulation
2.2Expressions & Formulae
2.3Linear Equations
2.4Quadratic Equations
2.5Proportion
3Sequences, Functions & Graphs
3.1Sequences
3.3Graphs
3.4Common Graphs
4Geometry
4.1Angles, Lines & Triangles
4.2Polygons
4.5Circle Properties
4.6Trigonometry & Pythagoras’ theorem
4.7Mensuration of 2D Shapes
4.83D Shapes & Volume
5Vectors & Transformation Geometry
6Statistics & Probability
6.1Statistical Measures
6.2Graphical Representation of Data
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