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### Course: Pre-algebra>Unit 7

Lesson 5: Finding mistakes in one-step equations

# Finding mistakes in one-step equations

Gain a deeper understanding of solving one-step equations by studying a correct and an incorrect example.
Solving one-step equations is all about using inverse operations on both sides of an equation to get the variable by itself. Answer the questions below to deepen your understanding of how to solve one-step equations.

## Cam solved this problem ${\text{correctly}}$‍ :

Solve for $x$:
$\phantom{\rule{2em}{0ex}}\begin{array}{rl}3x& =12\\ \\ \\ \frac{3x}{3}& =\frac{12}{3}& \\ \\ \\ x& =4& \\ \end{array}$
Why couldn't Cam just subtract $3$ to get the $x$ by itself?

## Brooke solved this problem ${\text{incorrectly}}$‍ :

Solve for $n$:
$\phantom{\rule{2em}{0ex}}\begin{array}{rl}n+4& =5\\ \\ \\ n+4+4& =5+4& \\ \\ \\ n& =9& \\ \end{array}$
Why is Brooke's work incorrect?

## Solve a problem on your own

Solve for $k$:
$k+4.2=5.9$
$k=\phantom{\rule{0.167em}{0ex}}$

## Want to join the conversation?

• Why do we make mistakes?
• Because humans arent the brightest
• how would you know the mistake
• idk i got it wrong
• how do you know your mistakes
• If the value of x in the answer does not make the original equation true, then there’s a mistake somewhere.

This means that checking whether or not your value of x makes the original equation true greatly reduces the frequency of mistakes on homework and tests.
• You can find out if you made a mistake if your answer doesn't not make the original equation true.
• how did you know the answer
• get better
• Why would u multiply