[Chapter 8.2] Evaluating and Simplifying Expressions: Order, Like Terms, Distributing | Pre-Algebra

Evaluating finds a value for a chosen input. Simplifying rewrites an expression so it keeps the same value for every input. This calm, step-by-step explainer shows how to do both, and why combining like terms is the distributive property read backward. You'll see: • evaluating in order, with PEMDAS • negative inputs and parentheses • two variables and a group • like terms, by letters and powers • why 3x + 5x = 8x • distributing before combining • a minus sign before parentheses • simplifying versus evaluating • five worked examples The full lesson, with worked examples and practice: https://mathbyfirstprinciples.org/pre... 0:00 Welcome, and what you'll learn 1:04 Evaluating in order 2:33 Negative inputs 3:05 Worked Example 1: a negative input 3:51 Two variables and a group 4:05 Worked Example 2: a group 4:47 Like terms 5:33 Why 3x + 5x = 8x 6:35 Combining like terms 7:17 Worked Example 3: x terms and constants 8:09 Distributing before combining 8:43 Worked Example 4: distribute, then combine 9:20 Dividing a group, and a leading minus 10:02 Worked Example 5: two groups 10:57 Simplifying versus evaluating 12:05 Key takeaways Narration is voiced with text-to-speech. Also available in Spanish, Hinglish, and Mandarin. #math #prealgebra