A linear equation is drawn as a straight ... We use substitution to calculate the values. For example y = 2x + 1 The y value is always '2 lots' of the x value plus 1. We replace the value of ...

This means equations are not always true. In the example above, \(3x + 5 = 11\), the only correct solution for \(x\) is 2. An identity is an equation which is always true, no matter what values ...