Review of Variables
| Site: | Saylor Academy |
| Course: | GKT101: General Knowledge for Teachers – Math |
| Book: | Review of Variables |
| Printed by: | Guest user |
| Date: | Tuesday, 20 May 2025, 8:18 AM |
Description
While arithmetic deals primarily with operations with numbers, in algebra, you will deal with expressions that involve variables–letters that represent real numbers. Watch this lecture series to review the concept of a variable and the conventional way to write basic expressions involving variables. Complete the interactive exercises.
What is a variable?
Source: Khan Academy, https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:foundation-algebra#x2f8bb11595b61c86:intro-variables
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License.
Why aren't we using the multiplication sign?
Evaluating an expression with one variable
Evaluating expressions with one variable - Questions
1. Evaluate \(\frac{n}{6} + 2 \) when \(n = 12 \).
2. Evaluate \(6 + x\) when \(x = 3\).
3. Evaluate \(\frac{15}{k}\) when \(k = 3 \).
4. Evaluate \(4g - 12\) when \(g = 5\).
5. Evaluate \(\frac{j}{4}\) when \(j = 12 \).
6. Evaluate \(c - 2\) when \(c = 7\).
7. Evaluate \(9 - \frac{8}{S} \) when \(S = 4\).
Answers
1. Let's substitute \(12\) for \(n\).
\(\frac{n}{6} + 2 \)
= \(\frac{12}{6} + 2 \)
= \( 2 + 2 \)
= \(4\)
2. Let's substitute \(3\) for \(x\).
\(6 + x\)
= \( 6 + 3\)
= \(9\)
3. Let's substitute \(3\) for \(k\).
\(\frac{15}{k} \)
= \(\frac{15}{3}\)
= \(5\)
4. Let's substitute \(5\) for \(g\).
\(4g - 12 \)
= \(4(5) - 12 \)
= \( 20 - 12\)
= \(8\)
5. Let's substitute \(12\) for \(j\).
\(\frac{j}{4} \)
= \(\frac{12}{4} \)
= \(3\)
6. Let's substitute \(7\) for \(c\).
\( c - 2\)
= \( 7 - 2\)
= \(5\)
7. Let's substitute \(4\) for \(S\).
\( 9 - \frac{8}{S}\)
= \( 9 - \frac{8}{4}\)
= \( 9 - 2\)
= \(7\)