Solve the Arithmetic Expression: 3+2-1 Step by Step

Order of Operations with Left-to-Right Calculation

3+21= 3+2-1=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Given that there are only addition and subtraction operations , we can solve from left to right
00:05 Let's start with the left exercise
00:14 We're left with a simple subtraction exercise
00:16 And that's the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

3+21= 3+2-1=

2

Step-by-step solution

According to the rules of the order of operations, given that the exercise only involves subtraction and addition operations, we solve the exercise from left to right:

3+2=5 3+2=5

51=4 5-1=4

3

Final Answer

4 4

Key Points to Remember

Essential concepts to master this topic
  • Rule: Addition and subtraction operations are performed from left to right
  • Technique: Calculate 3+2=5 3+2=5 first, then 51=4 5-1=4
  • Check: Verify by recalculating: 3+21=51=4 3+2-1 = 5-1 = 4

Common Mistakes

Avoid these frequent errors
  • Calculating subtraction before addition
    Don't solve 21=1 2-1=1 first, then 3+1=4 3+1=4 ! This ignores the left-to-right rule and can give wrong answers in more complex problems. Always work from left to right when operations have equal priority.

Practice Quiz

Test your knowledge with interactive questions

Solve the following equation:

\( 12+7-5\text{ }= \)

FAQ

Everything you need to know about this question

Why do I work from left to right instead of doing subtraction first?

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Addition and subtraction have equal priority in the order of operations! When operations have the same level of importance, we always work from left to right to get the correct answer.

What if I accidentally did the subtraction first and got the right answer?

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You got lucky this time! In this simple problem, both methods give 4. But in more complex expressions like 103+2 10-3+2 , the wrong order gives 5 instead of the correct answer 9.

How do I remember to work left to right?

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Think of it like reading a sentence - you read from left to right! When addition and subtraction appear together, treat them like words in a sentence and solve them in order.

Does this left-to-right rule apply to all math operations?

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It applies when operations have equal priority. Addition and subtraction are equal, multiplication and division are equal. But remember: PEMDAS still rules - do parentheses and exponents first!

What's the easiest way to check my work?

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Simply redo the calculation step by step! Write out each step: 3+21 3+2-1 becomes 51 5-1 becomes 4 4 .

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