Chapter 1: Problem 3
(1) Without using a calculator evaluate (a) \(1-2\) (b) \(-3-4\) (c) \(1-(-4)\) (d) \(-1-(-1)\) (e) \(-72-19\) (f) \(-53-(-48)\) (2) Confirm your answer to part (1) using a calculator.
Short Answer
Expert verified
(a) -1, (b) -7, (c) 5, (d) 0, (e) -91, (f) -5.
Step by step solution
01
Evaluate the Expression
(a) Evaluate the expression: Start with the expression: \(1 - 2\) Since 1 is positive and 2 is negative, subtract 2 from 1: \(1 - 2 = -1\)
02
Evaluate the Expression
(b) Evaluate the expression: Start with the expression: \(-3 - 4\) Both terms are negative, so add their absolute values and keep the negative sign: \(-3 - 4 = -7\)
03
Evaluate the Expression
(c) Evaluate the expression: Start with the expression: \(1 - (-4)\) Subtracting a negative number is the same as adding its positive equivalent: \(1 - (-4) = 1 + 4 = 5\)
04
Evaluate the Expression
(d) Evaluate the expression: Start with the expression: \(-1 - (-1)\) Subtracting a negative number is the same as adding its positive equivalent: \(-1 - (-1) = -1 + 1 = 0\)
05
Evaluate the Expression
(e) Evaluate the expression: Start with the expression: \(-72 - 19\) Both terms are negative, so add their absolute values and keep the negative sign: \(-72 - 19 = -91\)
06
Evaluate the Expression
(f) Evaluate the expression: Start with the expression: \(-53 - (-48)\) Subtracting a negative number is the same as adding its positive equivalent: \(-53 - (-48) = -53 + 48 = -5\)
07
Confirm with Calculator
Confirm each solution using a calculator by entering the original expressions and verifying that the results match the manual calculations.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
integer subtraction
Integer subtraction is a fundamental arithmetic operation that involves finding the difference between two whole numbers. When subtracting integers, it is important to recognize whether the numbers involved are positive or negative.
For example:
For example:
- In the expression: \(1 - 2\), since 1 is positive and 2 is negative, you subtract 2 from 1 to get \(1 - 2 = -1\).
- In the expression: \(-3 - 4\), where both terms are negative, you add their absolute values and keep the negative sign, giving \(-3 - 4 = -7\).
negative numbers
Negative numbers are numbers less than zero. They are denoted by a minus sign (-) in front of the number. Understanding how to work with negative numbers is crucial, especially in subtraction.
When dealing with negative numbers in subtraction:
When dealing with negative numbers in subtraction:
- Subtracting a negative number is the same as adding its positive equivalent. For instance, in the expression: \(1 - (-4)\), it becomes \(1 + 4 = 5\).
- Similarly, in the expression: \(-1 - (-1)\), it simplifies to \(-1 + 1 = 0\).
confirming calculations
Confirming your calculations is a vital step to ensure accuracy. After solving a problem manually, it is always a good practice to verify your result using a calculator.
For example, after manually solving the expression \(-72 - 19\) to get \(-91\), you should input the original expression into a calculator to check if the result matches.
This step helps to:
For example, after manually solving the expression \(-72 - 19\) to get \(-91\), you should input the original expression into a calculator to check if the result matches.
This step helps to:
- Identify any arithmetic errors made during manual calculations.
- Build confidence in your mathematical skills.
manual calculation
Manual calculation means performing arithmetic without the aid of a calculator. This practice is essential for developing strong mathematical foundational skills.
Here are some points to consider when doing manual calculations:
Here are some points to consider when doing manual calculations:
- Understand the operation rules: Knowing how to handle positive and negative numbers can simplify processes considerably.
- Pay attention to signs: Small mistakes with positive and negative signs can lead to incorrect results.
- Practice regularly: Consistent practice improves accuracy and speed.