2.5.9

Direct Proportion

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Direct Proportion

Two variables are directly proportional to one another if the size of one variable increases when the size of other increases.

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Directly proportional

  • If xx and yy are directly proportional to one another, we write:
    • xyx\large{\propto} y
  • Where \large \propto is the symbol of proportionality.
  • We can always write the equation:
    • x=kyx = ky
  • Where kk is called the constant of proportionality and is a non-zero number.
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Proportional

  • For example, the area of a square is proportional to the length of one side squared, so we can write
    • Ax2A=x2A\large{\propto} x^2 \rightarrow A=x^2
  • In this case, the constant of proportionality kk is equal to 1.

Jump to other topics

1Proof

2Algebra & Functions

2.1Powers & Roots

2.2Quadratic Equations

2.3Inequalities

2.4Polynomials

2.5Graphs

2.6Functions

2.7Transformation of Graphs

2.8Partial Fractions (A2 Only)

3Coordinate Geometry

4Sequences & Series

5Trigonometry

6Exponentials & Logarithms

7Differentiation

8Integration

9Numerical Methods

10Vectors

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