Negative Inputs

Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 6 of 51.

You substitute a negative number the same way as any other number. One thing matters more now: put the negative number in brackets.

Find $6-3n$ when n is -2. Write $6 - 3 \cdot \left(-2\right)$ . 3 times -2 is -6, so it is $6 - \left(-6\right)$ . Taking away -6 is adding 6. So it is $6+6$ , which is 12.

Without brackets, people often lose the minus sign. Then they work out $6-3\cdot 2$ and get 0.

Challenge

Find the value v of $5-2n$ when n is -4. Write v equal to the expression with (-4) in place of n, then work it out.

Start the lesson to read it in the interactive player and track your progress.

All lessons in Expressions & Data

1Variables and Expressions

What a Variable Is Writing Expressions Substituting a Value Expressions from Stories Recap: Expressions

4Combining Like Terms

Like Terms Letters and Numbers Negative Terms Two Letters Distribute, Then Collect Recap: Like Terms

7Probability

Chance as a Fraction The Complement Chance as a Percent Expected Count Recap: Probability

10Final Challenges

Final: Two Brackets Final: A Cubic Expression Final: The Phone Plan Final: A Decimal Mean Final: The Last Spin

2Evaluating Expressions

Negative InputsPowers in Expressions Formulas Recap: Evaluating

5Patterns and Sequences

Continuing a Pattern The Common Difference The nth Term Writing the Rule Recap: Sequences

8Tables and Charts

Reading a Table Totals and Differences Reading a Line Graph Percent of a Total Recap: Tables and Charts

3The Distributive Property

Number Properties Mental Math Distributing Letters Distributing a Minus Recap: Distributing

6Data and Averages

The Mean Mean with Negatives The Median The Mode The Range Recap: Data and Averages

9Perimeter and Area

Perimeter Area of a Rectangle Area of a Triangle Perimeter as an Expression Recap: Perimeter and Area