Controlled Experiments

Biology

1. Fundamental Concepts

Definition: Controlled experiments are scientific methods used to test hypotheses by manipulating one variable while keeping others constant.
Purpose: To establish cause-and-effect relationships and isolate the effects of a single variable on an outcome.
Variables: Independent variables are manipulated, dependent variables are measured, and controlled variables are kept constant.

2. Key Concepts

Basic Rule: $${\text{{Controlled Experiment}}} \implies {\text{{One Variable Manipulated}}}$$

Degree Preservation: The highest degree in the result matches input

Application: Used to combine expressions in physics/engineering

3. Examples

Example 1 (Basic)

Problem: Simplify $$(3x^2 + 2x) + (x^2 - 4x)$$

Step-by-Step Solution:

Group like terms: $$(3x^2 + x^2) + (2x - 4x)$$
Combine coefficients: $$4x^2 - 2x$$

Validation: Substitute x=1 → Original: 3+2+1-4=2; Simplified: 4-2=2 ✓

Example 2 (Intermediate)

Problem: $$(5y^3 - 2y + 4) + (3y^2 + 6y - 9)$$

Step-by-Step Solution:

Identify term hierarchy: y³, y², y, constants
Vertical alignment:

          5y³ -2y +4          + 3y² +6y -9          ------------------          5y³ +3y² +4y -5

Validation: Substitute y=1 → Original: 5-2+4+3+6-9=7; Simplified: 5+3+4-5=7 ✓

4. Problem-Solving Techniques

Visual Strategy: Color-code terms by degree
Error-Proofing: Use vertical alignment for complex expressions
Concept Reinforcement: Apply LASSO rule: Look for Algebraic SSame Structures Only