Algebra 1 / Unit 2: Solving Equations
2.1 One-Step Equations
Notes
An equation says two expressions are equal. To solve, get the variable alone by doing the inverse operation to both sides.
- Addition undoes subtraction: $x - 7 = 3 \Rightarrow x = 10$.
- Division undoes multiplication: $4x = 28 \Rightarrow x = 7$.
- Multiply by the reciprocal to undo a fraction: $\displaystyle \frac{2}{3}x = 8 \Rightarrow x = 8 \cdot \frac{3}{2} = 12$.
- Always check by substituting back in.
Practice
Solve $x + 9 = -4$.
Subtract 9 from both sides: $-4 - 9 = -13$.
Solve $-6y = 42$.
Divide both sides by $-6$.
Solve $\displaystyle \frac{n}{5} = -3$.
Multiply both sides by 5.
Ready for more? Take the Unit 2 test.