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Lesson 6: 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?

• how would you know the mistake
• idk i got it wrong
• Why do we make mistakes?
• Because humans arent the brightest
• 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.
• k+4.2= 5.9, k is 1.7 right, but how?
• 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.
(1 vote)
• Why would u multiply
• Later in algebra, you will encounter two-step equations and then equations with more than two steps, including equations with parentheses and/or the variable on both sides. A strong understanding of one-step equations will help you solve multi-step equations later on.
• a + 4 = 6

a + 4 - 4 = 6 - 4

a = 2

Is this correct? Why or why not?