Difficulty: Medium
Correct Answer: x - + =
Explanation:
Introduction / Context:
We must replace the four “*” slots (between the five numbers) with the four signs from exactly one option, in that order, with one of the slots being an equals sign. Standard operator precedence (×, ÷ before +, −) applies on each side of “=”.
Given Data / Assumptions:
Concept / Approach:
Test each sequence by inserting the symbols left→right. Only one should produce a true equality.
Step-by-Step Solution:
Option (c): “x − + =” → 2 × 4 − 3 + 4 = 9
Evaluate LHS with precedence: 2 × 4 = 8; then 8 − 3 + 4 = 9
Thus 9 = 9 is true.
Verification / Alternative check:
Other options fail, e.g., “+ × = −” gives 2 + 4 × 3 = 4 − 9 ⇒ 14 = −5 (false).
Why Other Options Are Wrong:
They either locate “=” in a place that makes one side negative while the other is clearly positive, or violate equality under proper precedence.
Common Pitfalls:
Ignoring precedence or inserting symbols out of order (not strictly left→right) leads to incorrect judgments.
Final Answer:
x - + =
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