Question

Carlos solved the equation below for x using inverse operations. His solution is x = 6.5. What mistake did Carlos make and how could he have checked his solution to know for certain that his answer is correct?
5x + 7.5 = 25
5x = 32.5
x = 6.5
What mistake did Carlos make with the steps he took to solve for x? Explain in detail

Answers

There are no human answers yet.
Answered by GPT-4o mini
Let's break down the solution Carlos attempted to find and analyze where he went wrong.

The original equation Carlos was tasked with solving is:

\[ 5x + 7.5 = 25 \]

**Step 1: Isolate the term with \(x\)**

Carlos aimed to isolate \(5x\) by subtracting \(7.5\) from both sides of the equation. The correct calculation should be:

\[ 5x + 7.5 - 7.5 = 25 - 7.5 \]

This simplifies to:

\[ 5x = 25 - 7.5 \]
\[ 5x = 17.5 \] (Not 32.5)

Carlos incorrectly concluded that \(5x = 32.5\), which was a mistake at this first step of isolating \(5x\).

**Step 2: Solve for \(x\)**

Next, he should have divided both sides by 5 to solve for \(x\):

\[ x = \frac{17.5}{5} \]
\[ x = 3.5 \] (Again, not 6.5)

**Carlos's Mistake Summary:**
1. Carlos incorrectly subtracted \(7.5\) from \(25\) and arrived at \(32.5\) instead of \(17.5\).
2. This fundamental miscalculation led to an incorrect value of \(x\).

**How Could He Have Checked His Solution?**
To verify the solution, Carlos could substitute his calculated value of \(x\) back into the original equation:

1. Substitute \(x = 6.5\) into the original equation \(5x + 7.5\):
\[
5(6.5) + 7.5 = 32.5 + 7.5 = 40
\]
The left side equals \(40\), but the original equation states it should equal \(25\).

Since the numbers do not match, Carlos would realize that \(x = 6.5\) is not a valid solution.

Instead, if he checked by substituting \(x = 3.5\):

\[
5(3.5) + 7.5 = 17.5 + 7.5 = 25
\]

The left side equals \(25\), confirming that \(x = 3.5\) is the correct solution.

In conclusion, Carlos's mistake was in incorrectly simplifying \(25 - 7.5\), and a way to avoid such mistakes is to always check the results by substituting the solution back into the original equation.

Related Questions