Solve the following.
53
To solve the given mathematical expression, we need to follow the order of operations. This rule is commonly known as BODMAS or PEMDAS. It dictates the sequence in which operations should be performed:
The given expression is:
\(78 + [-4 + (-3) \text{ of } \{27 + (-18 + (-2))\}]\)
Let's solve the expression step-by-step, starting with the innermost brackets and following the BODMAS rule.
Step 1: Innermost Brackets
First, solve the expression inside the innermost parentheses: \((-18 + (-2))\).
\(-18 + (-2) = -18 - 2 = -20\)
The expression now becomes:
\(78 + [-4 + (-3) \text{ of } \{27 + (-20)\}] \)
Step 2: Next Level Brackets
Next, solve the expression inside the curly braces: \(\{27 + (-20)\}\).
\(27 + (-20) = 27 - 20 = 7\)
The expression now becomes:
\(78 + [-4 + (-3) \text{ of } 7]\)
Step 3: Operation "of"
The term "\((-3) \text{ of } 7\)" means multiplication. So, calculate \((-3) \times 7\).
\(-3 \times 7 = -21\)
The expression now becomes:
\(78 + [-4 + (-21)]\)
Step 4: Remaining Brackets
Solve the expression inside the square brackets: \([-4 + (-21)]\).
\(-4 + (-21) = -4 - 21 = -25\)
The expression now becomes:
\(78 + (-25)\)
Step 5: Addition
Finally, perform the addition:
\(78 + (-25) = 78 - 25\)
\(78 - 25 = 53\)
The value of the expression is 53.
Let's list the steps and results:
| Step | Operation | Calculation | Expression Remaining |
|---|---|---|---|
| 1 | Innermost Brackets | \(-18 + (-2) = -20\) | \(78 + [-4 + (-3) \text{ of } \{27 + (-20)\}] \) |
| 2 | Next Brackets | \(27 + (-20) = 7\) | \(78 + [-4 + (-3) \text{ of } 7]\) |
| 3 | "of" (Multiplication) | \((-3) \times 7 = -21\) | \(78 + [-4 + (-21)]\) |
| 4 | Outer Brackets | \(-4 + (-21) = -25\) | \(78 + (-25)\) |
| 5 | Addition | \(78 + (-25) = 53\) | \(53\) |
The final result of the expression \(78 + [-4 + (-3) \text{ of } \{27 + (-18 + (-2))\}]\) is 53.
Here’s a quick table to review the symbols and operations encountered in this problem:
| Symbol | Meaning | Notes |
|---|---|---|
| \(+\) | Addition | Sum of two numbers |
| \(-\) | Subtraction | Difference between two numbers |
| \(()\), \(\{\}\), \([]\) | Brackets (Parentheses) | Operations inside must be done first, starting from innermost |
| "of" | Multiplication | Indicates multiplication, often used before fractions or percentages, and follows the 'O' in BODMAS/PEMDAS |
Understanding the correct order of operations is fundamental in mathematics. It ensures that everyone gets the same answer when evaluating an expression. While BODMAS is common in some regions, PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction) is used elsewhere. Both rules effectively convey the same hierarchy of operations:
Mistakes often happen when the left-to-right rule for multiplication/division and addition/subtraction is ignored. For example, in \(10 - 5 + 2\), you perform \(10 - 5 = 5\) first, then \(5 + 2 = 7\), not \(5 + 2 = 7\) first then \(10 - 7 = 3\). Similarly, in \(10 / 2 \times 5\), you perform \(10 / 2 = 5\) first, then \(5 \times 5 = 25\), not \(2 \times 5 = 10\) first then \(10 / 10 = 1\).
Practicing problems with nested brackets and different operations is the best way to master the order of operations.
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