Answer:
x = 3√10
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS 
- Brackets 
- Parenthesis 
- Exponents 
- Multiplication 
- Division 
- Addition 
- Subtraction 
Equality Properties 
- Multiplication Property of Equality 
- Division Property of Equality 
- Addition Property of Equality 
- Subtract Property of Equality 
Trigonometry
[Right Triangles Only] Pythagorean Theorem: a² + b² = c² 
- a is a leg 
- b is another leg 
- c is the hypotenuse 
Explanation:
Step 1: Identify Variables
Leg a = 9
Leg b = 3
Hypotenuse c = x
Step 2: Solve for x
- Substitute [PT]: 9² + 3² = x²
- Rearrange: x² = 9² + 3²
- Exponents: x² = 81 + 9
- Add: x² = 90
- Isolate x: x = 3√10