VG1
tall-og-algebra
Quiz
What is an equation?
An equation is a mathematical statement that two expressions are equal. Solving an equation means finding the value of the unknown.
What is an equation?
2x + 5 = 13
Solving equations
The goal is to isolate x. Whatever you do to one side, do to the other.
2x + 5 = 13 → 2x = 8 → x = 4
Check: 2·4+5 = 13 ✓
Check: 2·4+5 = 13 ✓
Steps
- Move all x-terms to the left
- Move all numbers to the right
- Divide by the coefficient of x
Systems of equations (two unknowns)
x + y = 5
x - y = 1
x - y = 1
Add: 2x = 6 → x = 3 → y = 2 → x=3, y=2
Always check your answer by substituting back into the original equation!
What is easy to understand and easy to use in all cases where it is needed, I have set forth.
— Al-Khwarizmi (780–850), father of algebra
🧠 Test yourself
Question 1 of 3
Solve: 3x + 6 = 21