Tim solved the question: X + 7 = -15
His steps were as follows: X + 7 = -15, add seven to both sides, X = -8, (-8) + 7 = -1
When he checked back, his solution didn’t work
What was his error?
“Grade” his paper and provide helpful feedback below. You can either include the steps to get the correct answer or describe what he did wrong
Tim's error was in his final step.
The correct steps to solve the equation X + 7 = -15 would be:
1. Subtract 7 from both sides of the equation:
X + 7 - 7 = -15 - 7
X = -22
Therefore, the correct solution to the equation is X = -22.
In terms of feedback, Tim's mistake occurred when he incorrectly subtracted 7 from -8 instead of following the correct steps of the equation. It is important to double-check all calculations to avoid errors. Additionally, encourage Tim to carefully review his work when checking solutions to equations, as this can help in identifying and correcting mistakes.
Tim's error was when he added seven to both sides of the equation, resulting in X = -8. However, in his final step, he incorrectly evaluated (-8) + 7 to be -1. The correct evaluation would be (-8) + 7 = -1. Hence, his final answer of -1 is incorrect.
To correct his error, Tim should have evaluated (-8) + 7 correctly as -1.
Feedback: Tim, you made a mistake in evaluating (-8) + 7. The correct expression should evaluate to -1, not -1. Therefore, the correct solution for the equation X + 7 = -15 is X = -8. Please be careful with your calculations, and always double-check your work to avoid such errors.
Tim made an error in his solution to the equation X + 7 = -15.
Here is the step-by-step breakdown of Tim's work:
1. Original equation: X + 7 = -15
2. Tim's first step was to add seven to both sides of the equation: X + 7 + 7 = -15 + 7. This simplifies to X = -8.
3. Tim then evaluated (-8) + 7, which led him to the incorrect answer of -1.
The error Tim made was in his third step. When solving the equation, he forgot to substitute the value of X (which he found correctly as -8) back into the original equation to verify if it satisfies the equation.
Here's how Tim could have correctly solved the equation:
1. Original equation: X + 7 = -15
2. Subtract 7 from both sides of the equation: X = -15 - 7. This simplifies to X = -22.
3. To check his solution, Tim should substitute the value of X (-22) back into the original equation: -22 + 7 = -15. This equation holds true, confirming that X = -22 is the correct solution.
Based on Tim's work, it is important to emphasize the importance of double-checking the solution by substituting it back into the original equation. By doing this, Tim could have identified his error and corrected it.