How can a transaction affect only one side of accounting equation?

A transaction can affect only one side of the accounting equation (Assets = Liabilities + Equity) when it involves a change in asset value without corresponding changes in liabilities or equity. For example, if a company receives cash from a customer for services provided, its cash asset increases while equity (through revenue) is also affected, but if no liabilities are created or settled, the equation remains balanced. However, if a company writes off an uncollectible account, it reduces assets without impacting liabilities, thus affecting only one side of the equation.