x^2-25/23 and b^2-18b+81/3b^2-12

• Explain in your own words what the meaning of domain is. Also, explain why a denominator cannot be zero.
• Find the domain for each of your two rational expressions.
• Write the domain of each rational expression in set notation (as demonstrated in the example).
• Do both of your rational expressions have excluded values in their domains? If yes, explain why they are to be excluded from the domains. If no, explain why no exclusions are necessary.