Examples of evaluating variable expressions | Introduction to algebra | Algebra I | Khan Academy

TL;DR

This video provides examples and explanations on how to simplify variable expressions by condensing multiplication symbols and substituting values for variables.

Transcript

Let's do some practice problems dealing with variable expressions. So these first problems say write the following in a more condensed form by leaving out the multiplication symbol or leaving out a multiplication symbol. So here we have 2 times 11x, so if we have 11 x's and then we're going to have 2 times those 11 x's, we're going to have 22 x's. ... Read More

Key Insights

• 😑 Removing the multiplication symbol and condensing expressions can simplify variable expressions.
• 🤬 Variables following a number can be written without the multiplication symbol for simplicity.
• ✖️ Multiplying fractions involves multiplying the numerators and denominators separately.
• 🥇 Combining variables and fractions can be done by placing the variable over the numerical value.
• 😑 Evaluating expressions involves substituting given values for variables.
• 🪈 The order of operations in algebra is multiplication/division before addition/subtraction.
• 👻 Understanding formulas allows for efficient calculation and concrete results.

Questions & Answers

Q: How can you condense an expression that includes a multiplication symbol?

To condense a multiplication expression, remove the multiplication symbol and multiply the numerical values. For example, 2 times 11x can be condensed to 22x.

Q: Can you simplify an expression with variables following a number?

Yes, expressions like 1.35 times y can be simplified by removing the multiplication sign, leaving it as 1.35y.

Q: How do you multiply fractions in algebra?

To multiply fractions, multiply the numerators together and multiply the denominators together. For example, 3 times 1/4 is equal to 3/4.

Q: How can variables and fractions be combined in an expression?

When dealing with variables following a fraction, you can write it as a simplified fraction by placing the variable over the numerical value. For example, 1/4 times z can be written as z/4.

Summary & Key Takeaways

• The video demonstrates how to condense multiplication expressions by removing the multiplication symbol. For example, 2 times 11x can be condensed to 22x.

• Another technique shown is simplifying expressions with variables following a number. For instance, 1.35 times y can be written as 1.35y.

• The video also covers multiplying fractions, where 3 times 1/4 equals 3/4, and multiplying variables with fractions, such as 1/4 times z being equal to z/4.

• The video concludes with examples of evaluating variable expressions by substituting given values for variables.