Question

Difficulty: MediumOrder of Operations and Number Properties

What is the value of the expression −3×(4−7)2+2423−4-3 \times (4 - 7)^2 + \frac{24}{2^3 - 4}?

  1. A
    8787
  2. B
    3333
  3. C
    −15-15
  4. −21-21Answer
  5. E
    −45-45

Answer

The correct answer is −21-21.
Following the order of operations, we first compute the term inside the parentheses: 4−7=−34 - 7 = -3. Next, we evaluate the exponents: (−3)2=9(-3)^2 = 9 and 23=82^3 = 8. This simplifies the expression to −3×9+248−4-3 \times 9 + \frac{24}{8 - 4}. Simplifying the denominator gives 8−4=48 - 4 = 4. We then perform the multiplication and division: −3×9=−27-3 \times 9 = -27 and 244=6\frac{24}{4} = 6. Adding these results together yields −27+6=−21-27 + 6 = -21.

Step-by-Step Solution

1
Evaluate the subtraction inside the parentheses.
4−7=−34 - 7 = -3
According to the order of operations, grouping symbols such as parentheses must be evaluated first.
2
Evaluate the exponential terms in the expression.
(−3)2=9(-3)^2 = 9 and 23=82^3 = 8
Exponents must be evaluated after parentheses and before multiplication, division, addition, or subtraction.
3
Simplify the denominator of the fraction.
8−4=48 - 4 = 4
The denominator must be fully simplified before dividing the numerator by it.
4
Perform multiplication and division from left to right.
−3×9=−27-3 \times 9 = -27 and 244=6\frac{24}{4} = 6
Multiplication and division have higher priority than addition and subtraction.
5
Perform the final addition.
−27+6=−21-27 + 6 = -21
Addition and subtraction are performed last.

Key Concept

Order of Operations (PEMDAS)
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