Find the student's error in solving the following inequality:

[tex]\[
\begin{array}{l}
31 \ \textless \ -5x + 6 \\
25 \ \textless \ -5x \\
-5 \ \textless \ x
\end{array}
\][/tex]

A. The student should have added 6 to both sides instead of subtracting it.
B. The student divided [tex]\(\frac{25}{-5}\)[/tex] incorrectly.
C. The student should have switched the direction of the inequality sign to get [tex]\(-5 \ \textgreater \ x\)[/tex] for a final answer.



Answer :

Certainly! Let's go through the solution step-by-step:

1. Initial Inequality:
[tex]\[ 31 < -5x + 6 \][/tex]

2. Isolate the term with [tex]\( x \)[/tex]:
To isolate the term with [tex]\( x \)[/tex], we need to remove the constant term on the right-hand side. We do this by subtracting 6 from both sides:
[tex]\[ 31 - 6 < -5x + 6 - 6 \][/tex]
Simplifying this, we get:
[tex]\[ 25 < -5x \][/tex]

3. Correcting the Mistake:
The student correctly isolated the term with [tex]\( x \)[/tex] up to this point. However, the mistake occurs in the next step.

4. Dividing by -5:
When we divide or multiply both sides of an inequality by a negative number, we must reverse the direction of the inequality sign. Therefore, we divide both sides by -5 and switch the inequality sign:
[tex]\[ \frac{25}{-5} > x \][/tex]
Simplifying this gives:
[tex]\[ -5 > x \][/tex]

5. Rewriting the Final Step:
The inequality [tex]\( -5 > x \)[/tex] can also be written as:
[tex]\[ x < -5 \][/tex]

### Summary of Errors:
- The student did not switch the direction of the inequality sign when dividing by a negative number. The correct division resulted in [tex]\( -5 > x \)[/tex], and should have been reported as [tex]\( x < -5 \)[/tex].
- The initial steps were correct until the division by -5, where the direction of the inequality was not properly switched.

### Correction:
- Correct final inequality: [tex]\( x < -5 \)[/tex]

Final Correct Inequality:
[tex]\[ x < -5 \][/tex]

Answer:

C. The student should have switched the direction of the inequality sign to get-5 > x for a final answer.

Step-by-step explanation:

31 < -5x+6

Step 1: Subtract 6 from each side.

31-6 < -5x+6-6

25 < -5x

Step 2 : Divide each side by -5, remembering to flip the inequality.

25/-5 > -5x/-5

-5 > x