Question

Evaluate each expression. $$ 9-4+2 $$

Short answer

7

Step-by-step solution

- Identify the operations

The expression given is: \[9 - 4 + 2\]Identify the operations to be performed. In this case, we have subtraction and addition.

- Subtract first

Perform the subtraction first according to the order of operations (PEMDAS/BODMAS). Subtract 4 from 9.\[9 - 4 = 5\]

- Add the result

Now add the result from Step 2 to 2.\[5 + 2 = 7\]

Key concepts

subtraction

Subtraction is one of the basic arithmetic operations. It represents taking away a particular quantity from another. In mathematical notation, subtraction is denoted by the minus symbol (-).
For example, in the expression \(9 - 4\), we subtract 4 from 9. Let's break it down:

• Start with the number 9.
• Subtract 4 from 9.
• This leaves you with a result of 5.

Subtraction tells us how much is left or how much we need to take away to reach a total. It's like having 9 apples and giving away 4. You'd have 5 apples left.

addition

Addition is another fundamental arithmetic operation. It represents combining or putting together two or more quantities. The symbol used for addition is the plus sign (+).
Using our example from the exercise, after performing the subtraction, we get 5. To complete the problem, we need to add 2 to this result: \(5 + 2\).
Here's how to think about it:

• Start with the result from the previous step, which is 5.
• Add 2 to 5.
• This gives us a final result of 7.

Addition is like collecting or accumulating objects. If you have 5 pencils and get 2 more, you'll end up with 7 pencils.

PEMDAS

The order of operations is essential in arithmetic to ensure that everyone gets the same result when solving expressions. The acronym PEMDAS helps remember this order:

• P - Parentheses
• E - Exponents
• M/D - Multiplication and Division (from left to right)
• A/S - Addition and Subtraction (from left to right)

In our exercise, the operations are subtraction and addition: \(9 - 4 + 2\). Since there are no parentheses or exponents, we move to subtraction and addition. According to PEMDAS, we perform subtraction and addition from left to right.
So, we first perform the subtraction \(9 - 4 = 5\), then addition \(5 + 2 = 7\).
Using PEMDAS ensures consistent and accurate results in all arithmetic problems.