Worked examples
Two examples
Example 1
Multiply out: −3(x − 4)
- Multiply −3 by each term, signs included: −3 × x = −3x, and −3 × (−4) = 12.
Answer: −3x + 12
Example 2
Simplify: 5x − (2x − 7)
- The minus sign changes the sign of every term inside: 5x − 2x + 7.
- Combine: 3x + 7.
Answer: 3x + 7
Where this is taught: Quiz 39: Polynomials and Factoring, “Subtracting polynomials, and the sign that catches everyone”
The drill
Ten problems
How many:
Type your answer like 3x^2 - 2x + 5: use ^ for a power, and write like terms together. Then press Check my answers at the bottom.Write each answer on the line. The answer key, with the reasoning, is on the last page.