Substitution and evaluating expressions

When studying "Evaluating expressions with two variables," focus on these key points:

1. Understanding Variables: Recognize that variables represent unknown values. In expressions with two variables (e.g., $x$ and $y$), each variable can take on different values.

2. Substitution: Learn how to substitute specific values for the variables in an expression. For example, if you have the expression $2x + 3y$ and $x = 1$, $y = 2$, substitute those values to evaluate the expression.

3. Order of Operations: Apply the order of operations (PEMDAS/BODMAS) when evaluating expressions. This ensures that calculations are done correctly.

4. Calculating Values: Become comfortable doing arithmetic with the substituted values in the expression, ensuring accurate calculations.

5. Graphical Interpretation: Understand how expressions with two variables can represent lines or curves on a graph, informing the relationship between the variables.

6. Practice: Engage in practice problems to reinforce understanding and improve skills in evaluating expressions with varying values for the variables.

By focusing on these points, you'll develop a solid grasp of evaluating expressions with two variables.

When studying "Evaluating expressions with two variables: fractions & decimals," focus on these key points:

1. Understanding Variables: Grasp the role of variables in expressions and how they can represent different values.

2. Order of Operations: Familiarize yourself with PEMDAS/BODMAS rules (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction) to evaluate expressions correctly.

3. Substituting Values: Learn how to substitute values for the variables in expressions, ensuring you replace each instance of a variable consistently.

4. Working with Fractions: Understand how to add, subtract, multiply, and divide fractions and how to handle them in expressions.

5. Handling Decimals: Know how to perform operations with decimals, including rounding and converting between fractions and decimals when necessary.

6. Combining Terms: Practice combining like terms and simplifying expressions where applicable.

7. Calculated Results: Focus on obtaining a final simplified result as a fraction, decimal, or mixed number.

8. Practice Problems: Engage with various practice problems that involve different operations with fractions and decimals to solidify your understanding.

By mastering these points, you will be proficient in evaluating expressions with two variables that include fractions and decimals.