Which of the following is an example for a Postfix expression?Optionsp+q-rpqr*+st-+p*q(r+s)- + pq

To determine which of the provided options is a valid Postfix expression, let’s first clarify what a Postfix expression (also known as Reverse Polish Notation, RPN) is. In Postfix notation, operators follow their operands. This means that for every operator, the required operands must appear before the operator itself.

Analyzing the Options

1. Option 1: p + q - r

   • This is an infix expression because operators are between operands.

2. Option 2: pqr+*

   • This looks like a Postfix expression. It can be parsed as (p + (q * r)).

3. Option 3: st-+

   • This also looks like a Postfix expression. It can be parsed as ((s - t) + ... ) but needs more context.

4. Option 4: p * q (r + s) -

   • This is an infix expression because of the parentheses.

5. Option 5: + pq

   • This is not a valid Postfix expression as the operator precedes the operands.

Conclusion

Based on the analysis above, the valid Postfix expressions among the options are Option 2: pqr+* and Option 3: st-+.

However, Option 2 is fully structured as a Postfix expression. The question requires one specific example of a Postfix expression.

Final Answer

The example of a valid Postfix expression is: pqr+*.