Linear relations > Linear functions
1234Linear functions

Theory

Take a look at the applet: Linear Function

If y is a linear function of x then the corresponding formula can be written as y = a x + b , where

  • a is the gradient, that is the increase (decrease) of per unit step ;

  • b is the y-intercept, the value of the function if x = 0 .

The graph of such a linear relationship is a straight line through ( 0 , b ) .
If you then increase the value of x by 1 , the function value will increase (or decrease) by a .
The gradient a is also called the slope, because this number determines the direction of the line.

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