Math Problem Statement

If 8 less than the product of a number and -3 is greater than 7, which of the following could be that number?

Solution

Let the unknown number be xx. Based on the problem, we can form the inequality:

3x8>7-3x - 8 > 7

Step 1: Simplify the inequality

Add 8 to both sides to isolate the term involving xx: 3x>15-3x > 15

Step 2: Solve for xx

Divide both sides by 3-3, remembering to reverse the inequality sign because we are dividing by a negative number: x<5x < -5

Step 3: Interpret the solution

The number xx must be less than -5. Therefore, any number less than 5-5 could satisfy this inequality.

Example values

Some possible values for xx are: x=6,7,10,etc.x = -6, -7, -10, \text{etc.}

Verify with a sample number

Take x=6x = -6: 3(6)8=188=10,10>7(True).-3(-6) - 8 = 18 - 8 = 10, \quad 10 > 7 \quad \text{(True)}.

Would you like further clarification or a graphical representation of the solution?


  1. How do you solve linear inequalities involving negative coefficients?
  2. Why does dividing by a negative number reverse the inequality?
  3. Can you graph the inequality x<5x < -5?
  4. What are other examples of numbers satisfying x<5x < -5?
  5. How would the solution change if the inequality was 3x8<7-3x - 8 < 7?

Tip: Always reverse the inequality sign when multiplying or dividing by a negative number!

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Inequalities
Negative Coefficients

Formulas

General linear inequality: ax + b > c

Theorems

Rule for reversing inequality when dividing by a negative number

Suitable Grade Level

Grades 6-8