Problem Solving
4-7Transforming Formulas
Overview
Solve a formula for one variable in terms of the others using equation-solving moves.
Key ideas
- Treat the target variable like a regular unknown.
- Undo operations using inverse operations.
- Keep everything else as letters.
Worked examples
Example 1
Problem. Solve P = 2l + 2w for l.
Solution. P − 2w = 2l → l = (P − 2w)/2.
Practice
Try each one. Click Show answer when ready.
- 1.
Solve d = rt for t.
- 2.
Solve A = (1/2)bh for h.
- 3.
Solve y = mx + b for x.
Challenge problems
A little tougher — great for test prep. Click Show answer when ready.
- 1.
Solve V = lwh for h.
- 2.
Solve A = ½h(b₁ + b₂) for b₁.